DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited.
DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited.
Although the words “he,” “him,” and “his” are used sparingly in this course to enhance communication, they are not intended to be gender driven or to affront or discriminate against anyone.
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PREFACE Special Publications (SPs) are manuals or catalogs that provide information of general benefit and career development. SPs have no associated assignments or tests.
This SP is available ONLY in electronic Portable Document Format from the following web site: http://www.advancement.cnet.navy.mil Refer questions about this SP to: E-mail<EMAIL_ADDRESS>Phone: Comm:<PHONE_NUMBER>, ext. 1728 DSN: 922-1001, ext. 1728/1809 FAX:<PHONE_NUMBER> Address: COMMANDING OFFICER NETPDTC N315 6490 SAUFLEY FIELD ROAD PENSACOLA FL 32509-5237
1998 Edition Prepared by FTCM Gilbert J. Cote’
NEETS Module 20—Master Glossary presents the combined glossaries from modules 1-18, the primary texts in the NEETS series. Definitions of terms used in NEETS are presented. Numbers in parenthesis ( ) indicate more than one definition for the same term. Numbers in brackets [ ] indicate the module number in which more information about the term may be found.
information. No significant changes have been made to content.
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“I am a United States Sailor. I will support and defend the Constitution of the United States of America and I will obey the orders of those appointed over me. I represent the fighting spirit of the Navy and those who have gone before me to defend freedom and democracy around the world. I proudly serve my country’s Navy combat team with honor, courage and commitment. I am committed to excellence and the fair treatment of all.”
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The Navy Electricity and Electronics Training Series (NEETS) was developed for use by personnel in many electrical- and electronic-related Navy ratings. Written by, and with the advice of, senior technicians in these ratings, this series provides beginners with fundamental electrical and electronic concepts through self-study. The presentation of this series is not oriented to any specific rating structure, but is divided into modules containing related information organized into traditional paths of instruction.
The series is designed to give small amounts of information that can be easily digested before advancing further into the more complex material. For a student just becoming acquainted with electricity or electronics, it is highly recommended that the modules be studied in their suggested sequence. While there is a listing of NEETS by module title, the following brief descriptions give a quick overview of how the individual modules flow together.
Module 1, Introduction to Matter, Energy, and Direct Current, introduces the course with a short history of electricity and electronics and proceeds into the characteristics of matter, energy, and direct current (dc). It also describes some of the general safety precautions and first-aid procedures that should be common knowledge for a person working in the field of electricity. Related safety hints are located throughout the rest of the series, as well.
Module 2, Introduction to Alternating Current and Transformers, is an introduction to alternating current (ac) and transformers, including basic ac theory and fundamentals of electromagnetism, inductance, capacitance, impedance, and transformers.
Module 3, Introduction to Circuit Protection, Control, and Measurement, encompasses circuit breakers, fuses, and current limiters used in circuit protection, as well as the theory and use of meters as electrical measuring devices.
Module 4, Introduction to Electrical Conductors, Wiring Techniques, and Schematic Reading, presents conductor usage, insulation used as wire covering, splicing, termination of wiring, soldering, and reading electrical wiring diagrams.
Module 5, Introduction to Generators and Motors, is an introduction to generators and motors, and covers the uses of ac and dc generators and motors in the conversion of electrical and mechanical energies.
Module 6, Introduction to Electronic Emission, Tubes, and Power Supplies, ties the first five modules together in an introduction to vacuum tubes and vacuum-tube power supplies.
Module 7, Introduction to Solid-State Devices and Power Supplies, is similar to module 6, but it is in reference to solid-state devices.
Module 8, Introduction to Amplifiers, covers amplifiers.
Module 9, Introduction to Wave-Generation and Wave-Shaping Circuits, discusses wave generation and wave-shaping circuits.
Module 10, Introduction to Wave Propagation, Transmission Lines, and Antennas, presents the characteristics of wave propagation, transmission lines, and antennas.
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Module 11, Microwave Principles, explains microwave oscillators, amplifiers, and waveguides.
Module 12, Modulation Principles, discusses the principles of modulation.
Module 13, Introduction to Number Systems and Logic Circuits, presents the fundamental concepts of number systems, Boolean algebra, and logic circuits, all of which pertain to digital computers.
Module 14, Introduction to Microelectronics, covers microelectronics technology and miniature and microminiature circuit repair.
Module 15, Principles of Synchros, Servos, and Gyros, provides the basic principles, operations, functions, and applications of synchro, servo, and gyro mechanisms.
Module 16, Introduction to Test Equipment, is an introduction to some of the more commonly used test equipments and their applications.
Module 17, Radio-Frequency Communications Principles, presents the fundamentals of a radio- frequency communications system.
Module 18, Radar Principles, covers the fundamentals of a radar system.
Module 19, The Technician's Handbook, is a handy reference of commonly used general information, such as electrical and electronic formulas, color coding, and naval supply system data.
Module 20, Master Glossary, is the glossary of terms for the series.
Module 21, Test Methods and Practices, describes basic test methods and practices.
Module 22, Introduction to Digital Computers, is an introduction to digital computers.
Module 23, Magnetic Recording, is an introduction to the use and maintenance of magnetic recorders and the concepts of recording on magnetic tape and disks.
Module 24, Introduction to Fiber Optics, is an introduction to fiber optics.
Embedded questions are inserted throughout each module, except for modules 19 and 20, which are reference books. If you have any difficulty in answering any of the questions, restudy the applicable section.
Although an attempt has been made to use simple language, various technical words and phrases have necessarily been included. Specific terms are defined in Module 20, Master Glossary.
Considerable emphasis has been placed on illustrations to provide a maximum amount of information. In some instances, a knowledge of basic algebra may be required.
Assignments are provided for each module, with the exceptions of Module 19, The Technician's Handbook; and Module 20, Master Glossary. Course descriptions and ordering information are in NAVEDTRA 12061, Catalog of Nonresident Training Courses.
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Throughout the text of this course and while using technical manuals associated with the equipment you will be working on, you will find the below notations at the end of some paragraphs. The notations are used to emphasize that safety hazards exist and care must be taken or observed.
AN OPERATING PROCEDURE, PRACTICE, OR CONDITION, ETC., WHICH MAY RESULT IN INJURY OR DEATH IF NOT CAREFULLY OBSERVED OR FOLLOWED.
AN OPERATING PROCEDURE, PRACTICE, OR CONDITION, ETC., WHICH MAY RESULT IN DAMAGE TO EQUIPMENT IF NOT CAREFULLY OBSERVED OR FOLLOWED.
An operating procedure, practice, or condition, etc., which is essential to emphasize.
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Course Title: NAVEDTRA: 14192 Date: We need some information about you: Rate/Rank and Name: SSN: Command/Unit Street Address: City: State/FPO: Zip Your comments, suggestions, etc.: Privacy Act Statement: Under authority of Title 5, USC 301, information regarding your military status is requested in processing your comments and in preparing a reply. This information will not be divulged without written authorization to anyone other than those within DOD for official use in determining performance. NETPDTC 1550/41 (Rev 4-00)
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This module presents the combined glossaries from modules 1 through 18, the primary texts in the NEETS series. Definitions of terms used in NEETS are presented in an alphabetical glossary. Numbers in parenthesis ( ) indicate more than one definition for the same term. Numbers in brackets [ ] indicate the module number in which more information about the term may be found. ABSORPTION(1) Dissipation of radio or sound waves as they interact with matter. (2) The absorbing of
light waves without reflection or refraction [10].
ABSORPTION, LAW OFIn Boolean algebra, the law which states that the odd term will be absorbed when a term is combined by logical multiplication with the logical sum of that term and another term, or when a term is combined by logical addition with the logical product of one term and another term (for example, A(A + B) = A + AB = A) [13].
ABSORPTION WAVEMETERAn instrument used to measure audio frequencies [16].
ACCELERATING ANODEAn electrode charged several thousand volts positive and used to accelerate electrons toward the front of a cathode-ray tube [6].
ACCELERATION SERVOSYSTEMA servosystem that controls the acceleration (rate of change in velocity) of a load [15].
ACCELEROMETERA device that measures the acceleration to which it is subjected and develops a signal proportional to it [15].
ACCEPTOR IMPURITYAn impurity which, when added to a semiconductor, accepts one electron from a neighboring atom and creates a hole in the lattice structure of the crystal. Also called TRIVALENT IMPURITY [7].
ACORN TUBEA very small tube with closely spaced electrodes and no base. The tube is connected to its circuits by short wire pins that are sealed in a glass or ceramic envelope. The acorn tube is used in low- power uhf circuits [6].
ACOUSTICSThe science of sound [10].
ACQUISITIONOperational phase of a fire-control or track radar during which the radar system searches a small volume of space in a prearranged pattern [18].
ACTIVE SATELLITEA satellite that amplifies the received signal and retransmits it back to earth [17].
ACTUATORThe part of a switch that is acted upon to cause the switch to change contact connections; for example, toggle, pushbutton, and rocker [3].
AFDSAn abbreviation for the amphibious flagship data system [17].
AIR-CONTROL PANELPanel that monitors the dry-air input at each user equipment [18].
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AIR-CORE TRANSFORMERA transformer composed of two or more coils that are wound around a nonmetallic core [2].
ALLOWANCE PARTS LIST (APL)Repair parts required for units having the equipment/ component listed [14].
ALLOYED JUNCTIONA junction formed by recrystallization of a molten region of P-type material on an N-type substrate, or vice versa [7].
ALPHAThe emitter-to-collector current gain in a common-base circuit [7].
ALTERNATING CURRENTAn electrical current that constantly changes amplitude and changes polarity at regular intervals [2].
ALTITUDEThe vertical distance of an aircraft or object above a given reference, such as ground or sea level [18].
ALUMINUM CREEP(1) The movement of aluminum wire from a point where pressure is applied. (2) The "retreat" of heated aluminum wire as it cools [4].
AMBIENT TEMPERATUREThe surrounding temperature such as the temperature of air surrounding a conductor in a compartment or within a piece of equipment [4].
AMBIGUOUS RETURNSEchoes that exceed the prt of a radar and appear at incorrect ranges [18].
AMERICAN WIRE GAUGE (AWG)The standards adopted in the United States for the measurement of wire sizes [4].
AMMETERAn instrument for measuring the amount of electron flow (in amperes) [1] [3] [6].
AMPEREThe basic unit of electrical current [1].
AMPERE-TURNThe magnetomotive force developed by 1 ampere of current flowing through a coil of one turn [8].
AMPERITE (BALLAST) TUBEA current-controlling resistance device designed to maintain substantially constant current over a specified range of variation in applied voltage or resistance of a series circuit [6].
AMPLIDYNEA special dc generator in which a small dc voltage applied to field windings controls a large output voltage from the generator. In effect, an amplidyne is a rotary amplifier that often times produces gain of approximately 10,000 [5].
AMPLIFICATION(1) The process of enlarging a signal in amplitude (as of voltage or current) [8]. (2) The ratio of output magnitude to input magnitude in a device that is intended to produce an output that is an enlarged reproduction of its input [6] [7].
AMPLIFICATION FACTORThe voltage gain of an amplifier with no load on the output [6] [7].
AMPLIFIERThe device that provides amplification (the increase in current, voltage, or power of a signal) without appreciably altering the original signal [7] [8].
AMPLITRONSee CROSS-FIELD AMPLIFIER [18].
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AMPLITUDEThe size of a signal as measured from a reference line to a maximum value above or below the line. Generally used to describe voltage, current, or power [8] [12].
AMPLITUDE DISTORTIONDistortion that is present in an amplifier when the amplitude of the output signal fails to follow exactly any increase or decrease in the amplitude of the input signal [6] [7].
AMPLITUDE MODULATIONAny method of varying the amplitude of an electromagnetic carrier frequency in accordance with the intelligence to be transmitted [12].
AMPLITUDE STABILITYAmplitude stability refers to the ability of the oscillator to maintain a constant amplitude in the output waveform [9].
AND CIRCUITSee AND GATE [13].
AND GATE(1) An electronic gate whose output is energized only when every input is in its prescribed state. An AND gate performs the function of the logical "AND"; also called an AND circuit. (2) A binary circuit, with two or more inputs and a single output, in which the output is a logic 1 only when all inputs are a logic 1 and the output is a logic 0 when any one of the inputs is a logic 0 [13].
ANGLE MODULATIONModulation in which the angle of a sine-wave carrier is varied by a modulating wave [12].
ANGLE OF INCIDENCEThe angle between the incident wave and the normal [10].
ANGLE OF INCLINATIONThe angular difference between the equatorial plane of the earth and the plane of orbit of the satellite [17].
ANGLE OF REFLECTIONThe angle between the reflected wave and the normal [10].
ANGLE OF REFRACTIONThe angle between the normal and the path of a wave through the second medium [10].
ANGSTROM UNITThe unit used to define the wavelength of light waves [10].
ANISOTROPICThe property of a radiator that allows it to emit strong radiation in one direction [10].
ANODE(1) A positive electrode of an electrochemical device (such as a primary or secondary electric cell) toward which the negative ions are drawn [1] [6) [7]. (2) The semiconductor-diode terminal that is positive with respect to the other terminal when the diode is biased in the forward direction [13].
ANTENNAA conductor or set of conductors used to radiate RF energy into space or to collect RF energy from space or to do both [10].
ANTENNA BEAM WIDTHWidth of a radar beam measured between half-power points [18].
ANTENNA COUPLERA device used for impedance matching between an antenna and a transmitter or receiver [17].
ANTENNA SYSTEMRoutes RF energy from the transmitter, radiates the energy into space, receives echoes, and routes the echoes to the receiver [18].
ANTIJAMMING CIRCUITAn electronic circuit used to minimize the effects of enemy countermeasures, thereby permitting radar echoes to be visible on the indicator [18].
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ANTISEIZE COMPOUNDA silicon-based, high-temperature lubricant applied to threaded components to aid in their removal after they have been subjected to rapid heating and cooling [4].
ANTITRANSMIT-RECEIVE TUBE (atr)A tube that isolates the transmitter from the antenna and receiver. Used in conjunction with a tr tube [18].
APERTURESee SLOT [11].
APOGEEThe point in the orbit of a satellite the greatest distance from the earth [17].
APPARENT DRIFTThe effect of the earth's rotation on a gyro that causes the spinning axis to appear to make one complete rotation in one day. Also called APPARENT PRECESSION or APPARENT ROTATION [15].
APPARENT POWERThat power apparently available for use in an ac circuit containing a reactive element. It is the product of effective voltage times effective current expressed in volt-amperes. It must be multiplied by the power factor to obtain true power available [2].
APPARENT PRECESSIONSee APPARENT DRIFT [15].
APPARENT ROTATIONSee APPARENT DRIFT [15].
ARC EXTINGUISHERThe part of a circuit breaker that confines and divides the arc which occurs when the contact of the circuit breaker opens [3].
ARMATURE(1) In a relay, the movable portion of the relay [3]. (2) The windings in which the output voltage is generated in a generator or in which input current creates a magnetic field that interacts with the main field in a motor [5].
ARMATURE LOSSESCopper losses, eddy current losses, and hysteresis losses that act to decrease the efficiency of armatures [5].
ARMATURE REACTIONThe effect in a dc generator of current in the armature creating a magnetic field that distorts the main field and causes a shift in the neutral plane [5].
ARRAY OF ARRAYSSame as COMBINATION ARRAY [10].
ARTIFICIAL TRANSMISSION LINEAn LC network that is designed to simulate characteristics of a transmission line [18].
ASBESTOSA noncombustible, nonconductive, fiber-like mineral used as an insulating material [4].
ASBESTOSISFibrosis of the lungs caused by inhalation of asbestos fibers [4].
A-SCOPEA radar display on which slant range is shown as the distance along a horizontal trace [18].
ASSEMBLYA number of parts or subassemblies, or any combination thereof, joined together to perform a specific function [17].
ASTABLE MULTIVIBRATORA multivibrator that has no stable state. Also called free-running because it alternates between two different output voltage levels during the time it is on. The frequency is determined by the RC time constant of the coupling circuit [9].
ASWTDSAn abbreviation for the antisubmarine warfare tactical data system [17].
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ASYMMETRICAL MULTIVIBRATORA multivibrator that generates rectangular waves [18].
ASYNCHRONOUSThe teletypewriter operation where the transmitter and receiver do not operate continuously [17].
ASYNCHRONOUS ORBITOne where the satellite does not rotate or move at the same speed as the earth [17].
ATDSAn abbreviation for the airborne tactical data system [17].
ATTENUATIONThe ability of a filter circuit to reduce the amplitude of unwanted frequencies to a level below that of the desired output frequency [9].
ATTRACTIONThe force that tends to make two objects approach each other. Attraction exists between two unlike magnetic poles (north and south) or between two unlike static charges [1].
AUDIO AMPLIFIERAn amplifier designed to amplify frequencies between 15 hertz (15 Hz) and 20 kilohertz (20 kHz) [8].
AUDIO-FREQUENCY-TONE SHIFTA system that uses amplitude modulation to change dc mark and space impulses into audio impulses [17].
AUTOMATIC GAIN CONTROLA circuit used to vary radar receiver gain for best reception of signals that have widely varying amplitudes [18].
AUTOMATIC TRACKINGTracking done by equipment that compares the direction of the antenna axis and the direction of the received signal and uses the difference (error) signal to reposition the antenna [17].
AUTOMATIC VOLUME/GAIN CONTROLA circuit used to limit variations in the output signal strength of a receiver [17].
AVALANCHE EFFECTA reverse breakdown effect in diodes that occurs at reverse voltages beyond 5 volts. The released electrons are accelerated by the electric field, which results in a release of more electrons in a chain or "avalanche" effect [7].
AVERAGE POWER(1) The peak power value averaged over the pulse-repetition time [12]. (2) Output power of a transmitter as measured from the start of one pulse to the start of the next pulse [18].
AVERAGE VALUE (OF AC)The average of all the instantaneous values of one-half cycle of alternating current [2].
AXISA straight line, either real or imaginary, passing through a body around which the body revolves [15].
AZIMUTHAngular measurement in the horizontal plane in a clockwise direction [18].
BACK RESISTANCEThe larger resistance value observed when you are checking the resistance of a semiconductor [16].
BALANCED MIXERA waveguide arrangement that resembles a T and uses crystals for coupling the output to a balanced transformer [18].
BALANCED PHASE DETECTORA circuit that controls the oscillator frequency (afc) [17].
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BANDPASS FILTERA filter that allows a narrow band of frequencies to pass through the circuit. Rejects or attenuates frequencies that are either higher or lower than the desired band of frequencies [9] [16].
BAND-REJECT FILTERA tuned circuit that does not pass a specified band of frequencies [9] [16].
BANDWIDTHThe difference between the highest usable frequency of a device (upper frequency limit) and the lowest usable frequency of the device (lower frequency limit) - measured at the half-power points [8] [9] [12] [15].
BARRETTERA type of bolometer characterized by an increase in resistance as the dissipated power rises [16].
BASEThe element in a transistor that controls the flow of current carriers [7].
BASE(1) A reference value. (2) A number that is multiplied by itself as many times as indicated by an exponent. (3) Same as radix. (4) The region between the emitter and collector of a transistor that receives minority carriers injected from the emitter. It is the element that corresponds to the control grid of an electron tube [13].
BASE-INJECTION MODULATORSimilar to a control-grid modulator. The gain of a transistor is varied by changing the bias on its base [12].
BATTERYA device for converting chemical energy into electrical energy [1].
BATTERY CAPACITYThe amount of energy available from a battery. Battery capacity is expressed in ampere-hours [1].
BAUDA measurement of speed based on the number of code elements or units per second [17].
BAYPart of an antenna array [10].
BEAMSee LOBE [18].
BEAM-LEAD CHIPSemiconductor chip with electrodes (leads) extended beyond the wafer [14].
BEAM-POWER TUBEAn electron tube in which the grids are aligned with the control grid. Special beam-forming plates are used to concentrate the electron stream into a beam. Because of this action, the beam-power tube has high power-handling capabilities [6].
BEARINGAn angular measurement of the direction of an object from a reference direction, such as true north [11].
BEARING RESOLUTIONAbility of a radar to distinguish between targets that are close together in bearing [18].
BEAT FREQUENCIESDifference and sum frequencies, which result from the combination of two separate frequencies [18].
BEAT FREQUENCYThe difference between the oscillator frequency and the unknown audio frequency [16].
BEAT-FREQUENCY OSCILLATORAn additional oscillator used in a receiver when it is receiving a cw signal. It provides an audible tone [17].
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BELThe unit that expresses the logarithmic ratio between the input and output of any given component, circuit, or system [16].
BETAThe ratio of a change in collector current to a corresponding change in base current when the collector voltage is constant in a common-emitter circuit [7].
BEVERAGE ANTENNAA horizontal, long-wire antenna designed for reception and transmission of low-frequency, vertically polarized ground waves [10].
BIASDifference of potential applied to a vacuum tube or transistor to establish a reference operating level [13].
BIAS CURRENTCurrent that flows through the base-emitter junction of a transistor and is adjusted to set the operating point of the transistor [13].
BIDIRECTIONAL ARRAYAn array that radiates in opposite directions along the line of maximum radiation [10].
BINARY(1) A number system that uses a base, or radix, of 2. Two digits (1 and 0) are used in the binary system. (2) Pertaining to a characteristic that involves the selection, choice, or condition in which there are only two possibilities. (3) A bistable multivibrator (flip-flop) is one example of a binary device [13].
BINARY CODEA method of representing two possible conditions (on or off, high or low, one or zero, the presence of a signal or absence of a signal). Electronic circuits designed to work in such a way that only two conditions are possible [13].
BINARY-CODEDThe state in which conditions are expressed by a series of binary digits (0's and 1's) [13].
BINARY DIGIT(1) A character that represents one of the two digits in the number system that has a radix of two. (2) Either of the digits 0 or 1 that may be used to represent the binary conditions of on or off [13].
BINARY NOTATIONSee BINARY NUMBER SYSTEM [13].
BINARY NUMBER SYSTEMA number system using two digits, symbols, or characters (usually 1 and 0) [13].
BINARY POINTThe radix point that separates powers of two and fractional powers of two in a binary number [13].
BISTABLEA device that is capable of assuming either one of two stable states [13].
BISTABLE MULTIVIBRATORA multivibrator that has two stable states. It remains in one of the states until a trigger is applied. It then flips to the other stable state and remains there until another trigger is applied. Also referred to as a FLIP-FLOP [9] [13].
BLACKThe reference color of equipment that passes unclassified information. It normally refers to patch panels [17].
BLEEDER CURRENTThe current through a bleeder resistor. In a voltage divider, bleeder current is usually determined by the 10 percent rule of thumb [1].
BLEEDER RESISTORA resistor used to draw a fixed current [1].
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BLIPSee PIP [18].
BLOCK DIAGRAMA diagram in which the major components of an equipment or a system are represented by squares, rectangles, or other geometric figures, and the normal order of progression of a signal or current flow is represented by lines [4].
BLOCKED-GRID KEYINGA method of keying in which the bias is varied to turn plate current on and off [12].
BLOCKINGA condition in an amplifier, caused by overdriving one or more stages, in which the amplifier is insensitive to small signals immediately after reception of a large signal [18].
BOLOMETERA loading device that undergoes changes in resistance as changes in dissipated power occur [16].
BONDING WIRESFine wires connecting the bonding pads of the chip to the external leads of the package [14].
BOOLEAN(1) Pertaining to the process used in the algebra formulated by George Boole. (2) Pertaining to the operations of formal logic [13].
BOOLEAN ALGEBRAA system of logic dealing with on-off circuit elements associated by such operators as the AND, OR, NAND, NOR, and NOT functions [13].
BOOLEAN LOGICSee BOOLEAN ALGEBRA [13].
BOUNDARY CONDITIONSThe two conditions that the E-field and H-field within a waveguide must meet before energy will travel down the waveguide. The E-field must be perpendicular to the walls and the H-field must be in closed loops, parallel to the walls, and perpendicular to the E-field [11].
BRANCHAn individual current path in a parallel circuit [1] [4].
BREAKIn a switch, the number of breaks refers to the number of points at which the switch opens the circuit; for example, single break and double break [3].
BREAKDOWNThe phenomenon occurring in a reverse-biased semiconductor diode. The start of the phenomenon is observed as a transition from a high dynamic resistance to one of substantially lower dynamic resistance. This is done to boost the reverse current [7].
BRIGHTNESS CONTROLThe name given to the potentiometer used to vary the potential applied to the control grid of a CRT [6].
BROADSIDE ARRAYAn array in which the direction of maximum radiation is perpendicular to the plane containing the elements [10] [18].
BRUSHESSliding contacts, usually carbon, that make electrical connection to the rotating part of a motor or generator [5].
BUFFERA voltage amplifier used between the oscillator and power amplifier [12].
BUFFER AMPLIFIERAn amplifier that isolates one circuit from another. It decreases the loading effect on an oscillator by reducing the interaction between the load and the oscillator [9] [18].
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BUILT-IN TEST EQUIPMENT (BITE)A permanently mounted device that is used expressly for testing an equipment or system [14].
BUNCHER CAVITYThe input resonant cavity in a conventional klystron oscillator [11].
BUNCHER GRIDIn a velocity-modulated tube, the grid that concentrates the electrons in the electron beam into bunches [11].
BURNISHING TOOLA tool used to clean and polish contacts on a relay [3].
BUS BARA heavy copper strap or bar used to connect several circuits together when a large current- carrying capacity is required [4].
BYPASS CAPACITORA capacitor used to transfer unwanted signals out of a circuit; for example, coupling an unwanted signal to ground. Also called a DECOUPLING CAPACITOR [8].
CABLEEither a stranded conductor (single-conductor cable) or a combination of conductors insulated from one another (multiple conductor cable). Small sizes are commonly referred to as stranded wire or as cords [4].
CABLE HARNESSA group of wires or ribbons of wiring used to interconnect electronic systems and subsystems [14].
CAPACITANCEThe property of an electrical circuit that opposes changes in voltage [2].
CAPACITIVE REACTANCEThe opposition, expressed in ohms, offered to the flow of an alternating current by capacitance. The symbol for capacitive reactance is X C [2] [9].
CAPACITORAn electrical device capable of storing electrical energy in an electrostatic field [2].
CAPACITOR FILTERThis filter is used on extremely high-voltage, low-current power supplies and also where the ripple frequency is not critical [7].
CAPACITOR-START MOTORA type of single-phase, ac induction motor in which a starting winding and a capacitor are placed in series to start the motor. The values of XC and R are such that the main-winding and starting-winding currents are nearly 90 degrees apart and the starting torque is produced as in a two-phase motor [5].
CARBON MICROPHONEA microphone in which sound waves vary the resistance of a pile of carbon granules. May be single-button or double-button [12].
CARDIOPULMONARY RESUSCITATIONProcedure designed to restore breathing after cardiac arrest. Includes clearing air passages to lungs and heart massage [1].
CARRIER FREQUENCYThe frequency of an unmodulated transmitter output [12] [18].
CARRIER-CONTROLLED APPROACHA shipboard radar system used to guide aircraft to safe landings in poor visibility conditions [18].
CARRY(1) One or more digits, produced in connection with an arithmetic operation, that is/are forwarded to another digit place for processing there. (2) The number represented by the digit or digits in (1) above [13].
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CATCHER GRIDIn a velocity-modulated tube, a grid on which the spaced electron groups induce a signal. The output of the tube is taken from the catcher grid [11].
CATHODE(1) In an electron tube the electrode that is the source of current flow [6]. (2) The general name for any negative electrode [1]. (3) The negative terminal of a forward-biased semiconductor diode, which is the source of the electrons [7].
CATHODE BIASThe method of biasing a vacuum tube in which the biasing resistor is placed in the common-cathode return circuit, thereby making the cathode more positive with respect to ground [6].
CATHODE KEYINGA system in which the cathode circuit is interrupted so that neither grid current nor plate current can flow [12].
CATHODE MODULATORVoltage on the cathode is varied to produce the modulation envelope [12].
CATHODE-RAY TUBE (CRT)An electron tube that has an electron gun, a deflection system, and a screen. This tube is used to display visual electronic signals [6].
CATHODE SPUTTERINGA process of producing thin film components [14].
CAVITY RESONATORA space totally enclosed by a metallic conductor and supplied with energy in such a way that it becomes a source of electromagnetic oscillations. The size and shape of the enclosure determine the resonant frequency [11].
CAVITY WAVEMETERAn instrument used to measure microwave frequencies [16].
CELLA single unit that transforms chemical energy into electrical energy. Batteries are made up of cells [1].
CENTER-FEED METHODConnecting the center of an antenna to a transmission line which is then connected to the final (output) stage of the transmitter [10].
CENTIMETER CUBEA unit of volume of large rectangular or square conductors. The cross-sectional area equals 1 square centimeter with a length of 1 centimeter [4].
CHANNELA carrier frequency assignment, usually with a fixed bandwidth [12].
CHARACTERA letter, digit, or other symbol that is used as part of the organization, control, or representation of information [13].
CHARACTERISTIC IMPEDANCEThe ratio of voltage to current at any given point on a transmission line represented by a value of impedance [10].
CHARGERepresents electrical energy. A material having an excess of electrons is said to have a negative charge. A material having a shortage of electrons is said to have a positive charge [1].
CHARGE CYCLEThe period of time that a capacitor in an electrical circuit is storing a charge [2].
CHOKEAn inductor used to impede the flow of pulsating dc or ac by means of self-inductance [6] [7].
CHOKE JOINTA joint between two sections of waveguide that provides a good electrical connection without power losses or reflections [11].
CIRCUITThe complete path of an electric current [1].
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CIRCULAR MILAn area equal to that of a circle with a diameter of 0.001 inch. It is used for measuring the cross-sectional area of wires [1].
CIRCULAR MIL-FOOTA unit of volume of a conductor having a cross-sectional area of 1 circular mil and a length of 1 foot [4].
CLAMPERA circuit in which either the upper or lower extremity of a waveform is fixed at a desired value [9].
CLASS A AMPLIFIER OPERATIONThe type of operation in which the amplifier is biased so that variations in input signal polarities occur within the limits of cutoff and saturation [7].
CLASS AB AMPLIFIER OPERATIONThe type of operation in which the amplifier is biased so that collector current is cut off for a portion of the alternation of the input signal [7].
CLASS B AMPLIFIER OPERATIONThe type of operation in which the amplifier is biased so that collector current is cut off for one-half of the input signal [7].
CLASS C AMPLIFIER OPERATIONThe type of operation in which the amplifier is biased so that collector current is cut off for more than one-half of the input signal [7] [13].
CLUTTERConfusing, unwanted echoes that interfere with the observation of desired signals on a radar indicator [18].
COAXIAL CABLECable in which the center conductor is separated from an outer conductor by a dielectric material; used in RF transmission [4].
COAXIAL LINEA type of transmission line that contains two concentric conductors [10].
CODEIn teletypewriter operation, code is a combination of mark and space conditions representing symbols, figures, or letters [17].
COEFFICIENT OF COUPLINGAn expression of the extent to which two inductors are coupled by magnetic lines of force. This is expressed as a decimal or percentage of maximum possible coupling and represented by the letter K [2].
COHERENCEA definite phase relationship between two energy waves, such as transmitted frequency and reference frequency [18].
COHERENTRadiation on one frequency [17].
COHERENT OSCILLATORIn cw radar an oscillator that supplies phase references to provide coherent video from target returns [18].
COILAn inductive device made by looping turns of wire around a core [2].
COLD-CATHODE TUBEA gas-filled electron tube that conducts without the use of filaments. Cold- cathode tubes are used as voltage regulators [6].
COLLECTORThe element in a transistor that collects the current carriers [7].
COLLECTOR-INJECTION MODULATORThe transistor equivalent of a plate modulator. Modulating voltage is applied to a collector circuit [12].
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COLLINEAR ARRAYAn array with all the elements in a straight line. Maximum radiation is perpendicular to the axis of the elements [10].
COMBINATION ARRAYAn array system that uses the characteristics of more than one array [10].
COMBINATION CIRCUITA series-parallel circuit [1].
COMBINATION PEAKINGA technique in which a combination of peaking coils in series and parallel (shunt) with the output signal path is used to improve high-frequency response [8].
COMMON BASEA transistor circuit in which the base electrode is the common element to both input and output circuits [7].
COMMON-BASE DETECTORAn amplifying detector in which detection occurs in the emitter-base junction and amplification occurs at the output of the collector junction [12].
COMMON COLLECTORA transistor circuit configuration in which the collector is the element common to both the input and the output circuits [7].
COMMON EMITTERA circuit configuration in which the emitter is the element common to both the input and the output circuits [7].
COMMON-EMITTER DETECTOROften used in receivers to supply detected and amplified output. The emitter-base junction acts as the detector [12].
COMMON IDENTITIES LAWIn Boolean algebra this law states that anytime the expression A(A + B) = AB or A + AB = A + B appears, it can immediately be simplified to AB without going through the process of using the distributive law, complementary law, or the law of union to simplify [13].
COMMUTATIONThe act of a commutator in converting generator output from an ac voltage to a dc voltage [5].
COMMUTATIVE LAWIn Boolean algebra this law states that changing the order of the terms in an equation will not affect the value of the equation. Example: A + B = B + A; A • B = B • A [13].
COMMUTATORA mechanical device that reverses armature connections in motors and generators at the proper instant so that current continues to flow in only one direction. In effect, the commutator changes ac to dc [5].
COMPARATORAn equipment that compares incoming signals and selects the strongest to be fed to a teletypewriter through a patch panel. This is used in diversity operation [17].
COMPENSATING WINDINGSWindings embedded in slots in pole pieces, connected in series with the armature, whose magnetic field opposes the armature field and cancels armature reaction [5].
COMPENSATIONThe process of overcoming the problems associated with high frequencies in an amplifier [8].
COMPLEMENTA number or state that is the opposite of a specified number or state. The negative of a number is often represented by its complement [13].
COMPLEMENTARY (SECONDARY) COLORS OF LIGHTThe colors of light produced when two of the primaries are mixed in overlapping beams of light. The complementary colors of light are magenta, yellow, and cyan [10].
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COMPLEMENTARY LAWIn Boolean algebra this law states that the logical addition of a quantity and its complement will result in 1 and the logical multiplication of a quantity and its complement will result in a product of 0 [13].
COMPLEMENT NUMBERA number that when added to another number gives a sum equal to the base of the number system of operation. For example, in the decimal number system, the complement of 1 is 9 [13].
 (2) A wave that is produced by combining two or more pure tones at the same time [10] [12].
COMPOUND-WOUND MOTORS AND GENERATORSMachines that have a series field in addition to a shunt field. Such machines have characteristics of both series- and shunt-wound machines [5].
COMPRESSION WAVESLongitudinal waves that have been compressed (made more dense) as they move away from the source [10].
COMPUTERA data processor that can perform substantial computation, including numerous arithmetic or logic operations, without intervention by a human operator during the run [13].
CONCURRENTPertaining to the occurrence of two or more events or activities within the same specified interval of time [13].
CONDUCTANCEThe ability of a material to conduct or carry an electric current. It is the reciprocal of the resistance of the material and is expressed in mhos or siemens [1] [4] [10].
CONDUCTION BANDA partially filled energy band in which electrons can move freely [7].
CONDUCTIVITYThe ease with which a substance transmits electricity [1].
CONDUCTOR(1) A material with a large number of free electrons. (2) A material that easily permits electric current to flow [1].
CONDUITA tubular raceway, usually metal or plastic, for holding wires or cables [4].
CONICAL SCANNINGScanning in which the movement of the beam describes a cone, the axis of which coincides with that of the reflector [18].
CONNECTED ARRAYAnother term for DRIVEN ARRAY [10].
CONTACTIn radar, an object that reflects RF energy; target [18].
CONTINUITYAn uninterrupted, complete path for current flow [3] [16].
CONTINUOUS-WAVE KEYINGThe on-off keying of a carrier [12].
CONTROL DIFFERENTIAL TRANSMITTER (CDX)A type of synchro that transmits angular information equal to the algebraic sum or difference of the electrical input supplied to its stator, the mechanical input supplied to its stator, and the mechanical input supplied to its rotor. The output is an electrical voltage taken from the rotor windings [15].
CONTROL GRIDThe electrode of a vacuum tube, other than a diode, upon which a signal voltage is impressed to regulate the plate current [6].
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CONTROL-GRID MODULATORUses a variation of grid bias to vary the instantaneous plate voltage and current. The modulating signal is applied to the control grid [12].
CONTROL SYNCHRO SYSTEMSSynchro systems that contain control synchros and are used to control large amounts of power with a high degree of accuracy. The electrical outputs of these systems control servosystems, which in turn generate the required power to move heavy loads [15].
CONTROL SYSTEMA group of components systematically organized to perform a specific control purpose. These systems are categorized as either closed- or open-loop systems. The main difference between the two is that the closed-loop system contains some form of feedback [15].
CONTROL TRANSFORMER (CT)A type of synchro that compares two signals: the electrical signal applied to its stator and the mechanical signal applied to its rotor. The output is an electrical voltage, which is taken from the rotor winding and is used to control a power-amplifying device. The phase and amplitude of the output voltage depends on the angular position of the rotor with respect to the magnetic field of the stator [15].
CONTROL TRANSMITTER (CX)A type of synchro that converts a mechanical input, which is the angular position of its rotor, into an electrical output signal. The output is taken from the stator windings and is used to drive either a CDX or CT [15].
CONVERTERIn communications, equipment that changes the audio output of a receiver to dc pulses. These pulses are fed to a tty to indicate marks and spaces [17].
COOKIE-CUTTER TUNERA mechanical magnetron tuning device that changes the frequency by changing the capacitance of the anode cavities [11].
COPPER LOSS (I2R LOSS)The power lost because of the resistance of the conductors. In transformers the power lost because of current flow (I) through the resistance (R) of the windings [2] [10] [11].
CORDWOOD MODULEA method of increasing the number of discrete components in a given space. Resembles wood stacked for a fireplace [14].
COREAny material that affords a path for magnetic flux lines in a coil [2].
CORNER-REFLECTOR ANTENNAA half-wave antenna with a reflector consisting of two flat metal surfaces meeting at an angle behind the radiator [10] [18].
CORONAThe discharge of electricity from a conductor with a high potential [4].
CORRECTIVE MAINTENANCEIncludes location and repair of equipment failures [16].
CORRESPONDENCEThe term given to the positions of the rotors of a synchro transmitter and a synchro receiver when both rotors are on 0 degree or displaced from 0 degree by the same angle [15].
COULOMBA measure of the quantity of electricity. One coulomb is equal to 6.28 x 1018 electrons [1].
COULOMB'S LAWAlso called the LAW OF ELECTRIC CHARGES or the LAW OF ELECTROSTATIC ATTRACTION. Coulomb's Law states that charged bodies attract or repel each other with a force that is directly proportional to the product of their individual charges and inversely proportional to the square of the distance between them [1].
COUNTERA circuit that counts input pulses [9].
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COUNTER EMFThe voltage generated within a coil by a moving magnetic field cutting across the coil itself. This voltage is in opposition (counter) to the moving field that created it. Counter emf is present in every motor, generator, transformer, or other inductance winding whenever an alternating current flows [2] [5].
COUNTERPOISEA network of wire connected to a quarter-wave antenna at one end. The network provides the equivalent of an additional one-fourth wavelength [10].
COUPLINGThe process of transferring energy from one point in a circuit to another point, or from one circuit to another [8].
COUPLING CAPACITORA capacitor used to couple signals [8].
COUPLING DEVICEA coupling coil that connects the transmitter to the feeder [10].
COVALENT BONDA type of linkage between atoms in which the atoms share valence electrons [7].
CPRCardiopulmonary Resuscitation [1].
CREST (TOP)The peak of the positive alternation (maximum value above the line) of a wave [10].
CRITICAL ANGLEThe maximum angle at which radio waves can be transmitted and still be refracted back to earth [10].
CRITICAL FREQUENCYThe maximum frequency at which a radio wave can be transmitted vertically and still be refracted back to earth [10].
CROSSED-FIELD AMPLIFIERA high-power electron tube that converts dc to microwave power by a combination of crossed electric and magnetic fields [18].
CROSS-SECTIONAL AREAThe area of a "slice" of an object. When applied to electrical conductors it is usually expressed in circular mils [1].
CROWN-OF-THORNS TUNERSee SPROCKET TUNER [11].
CRYSTALA natural substance, such as quartz or tourmaline, that is capable of producing a voltage when under physical stress or of producing physical movement when a voltage is applied [9].
CRYSTAL FURNACEA device for artificially growing cylindrical crystals to be used in the production of semiconductor substrates [14].
CRYSTAL MICROPHONEA microphone that uses the piezoelectric effect of crystalline matter to generate a voltage from sound waves [12].
CRYSTAL OVENA closed oven maintained at a constant temperature in which a crystal and its holder are enclosed to reduce frequency drift [9].
CURRENTThe movement of electrons past a reference point. The passage of electrons through a conductor. Measured in amperes [1].
CURRENT-FEED METHODSame as CENTER-FEED METHOD [10].
CURRENT RATINGThe safe current-carrying capacity of a wire or cable on a continuous basis [4].
CURRENT REGULATORA circuit that provides a constant current output [7].
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CURRENT STANDING-WAVE RATIO (ISWR)The ratio of maximum to minimum current along a transmission line [10].
CUSPSSharp phase reversals [12].
CUTOFFThe condition in a tube or transistor whereby the reverse bias prevents current flow [13].
CUTOFF FREQUENCYThe frequency at which the attenuation of a waveguide increases sharply and below which a traveling wave in a given mode cannot be maintained. A frequency with a half- wavelength that is greater than the wide dimension of a waveguide [11].
CW DEMODULATORA circuit that detects the presence of RF oscillations and converts them into a useful form [12].
CYCLE(1) One complete positive and one complete negative alternation of a current or voltage [2] [10]. (2) A 360-degree rotation of a vector generating a sine wave [12].
CYLINDRICAL PARABOLIC REFLECTORA parabolically shaped reflector that resembles part of a cylinder [18].
DAMPED WAVEA sinusoidal wave in which the amplitude steadily decreases with time. Often associated with energy loss [9].
DAMPING(1) The process of smoothing out oscillations. (2) In a meter, this process is used to keep the pointer of the meter from overshooting the correct reading [3]. (3) A mechanical or electrical technique used in synchro receivers to prevent the rotor from oscillating or spinning. Damping is also used in servosystems to minimize overshoot of the load [15] [16].
D'ARSONVAL METER MOVEMENTThe permanent-magnet moving-coil movement used in most meters [3] [16].
DATA PROCESSINGThe execution of a systematic sequence of operations performed upon data. Synonymous with information processing [13].
DATA TRANSMISSIONThe transfer of information from one place to another or from one part of a system to another [15].
dBmAn abbreviation used to represent power levels above or below a 1-milliwatt reference [16].
DEAD SHORTA short circuit having minimum resistance [1].
DECIMALPertaining to the number representation system with a radix of ten [13].
DECIMAL DIGITIn decimal notation, one of the characters 0 through 9 [13].
DECIMAL NOTATIONA fixed radix notation where the radix is ten [13].
DECIMAL NUMERALA decimal representation of a number [13].
DECIMAL POINTThe radix point in decimal representation [13].
DECOUPLING CAPACITORA capacitor used to transfer unwanted signals out of a circuit; for example, coupling an unwanted signal to ground. Also called a BYPASS CAPACITOR [8].
DEFLECTION COILSIn a cathode-ray tube, coils used to bend an electron beam a desired amount [18].
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DEFLECTION PLATESTwo pairs of parallel electrodes, one pair set forward of the other and at right angles to each other, parallel to the axis of the electron stream within an electrostatic cathode-ray tube [6].
DEGENERATIONThe process whereby a part of the output signal of an amplifying device is returned to its input circuit in such a manner that it tends to cancel part of the input [7].
DEGENERATIVE FEEDBACKFeedback in which the feedback signal is out of phase with the input signal; also called NEGATIVE FEEDBACK [8].
DEGREE-OF-FREEDOMThe number of axes about which a gyro is free to precess [15].
DEIONIZATION POTENTIALThe potential at which ionization of the gas within a gas-filled tube ceases and conduction stops; also referred to as extinction potential [6].
DEIONIZATION TIMEIn a spark gap, the time required for ionized gas to return to its neutral state after the spark is removed [18].
DELTAA three-phase connection in which windings are connected end-to-end, forming a closed loop that resembles the Greek letter delta. A separate phase wire is then connected to each of the three junctions [5].
DEMODULATIONThe removal of intelligence from a transmission medium [12].
DEMODULATORA circuit used in servosystems to convert an ac signal to a dc signal. The magnitude of the dc output is determined by the magnitude of the ac input signal, and its polarity is determined by whether the ac input signal is in or out of phase with the ac reference voltage [15].
DeMORGAN'S THEOREMA theorem which states that the inversion of a series of AND applications is equal to the same series of inverted OR applications, or the inversion of a series of OR applications is equal to the same series of inverted AND applications. In symbols,
DENSITY(1) The compactness of a substance. (2) Mass per unit volume [10].
DEPLETION REGIONThe region in a semiconductor where essentially all free electrons and holes have been swept out by the electrostatic field which exists there [7].
DEPOT-LEVEL MAINTENANCE (SM&R CODE D)Supports SM&R Code I and SM&R Code O activities through extensive shop facilities and equipment and highly skilled personnel [14].
DESIGNATIONOperational phase of a fire-control or track radar during which the radar is directed to the general direction of a desired target [18].
DETECTIONThe separation of low-frequency (audio) intelligence from the high-frequency carrier [17].
DETECTORA mixer or converter in a superheterodyne receiver [18].
DICEUncased chips [14].
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DIE BONDINGProcess of mounting a chip to a package [14].
DIELECTRICAn insulator; a term applied to the insulating material between the plates of a capacitor [2].
DIELECTRIC CONSTANTThe ratio of a given dielectric to the dielectric value of air [2] [11].
DIELECTRIC FIELDThe space between and around charged bodies in which their influence is felt. Also called ELECTRIC FIELD OF FORCE or an ELECTROSTATIC FIELD [1].
DIELECTRIC HEATINGThe heating of an insulating material by a high-frequency electric field [10].
DIELECTRIC HYSTERESIS LOSSPower loss of a capacitor because of the changes in orientation of electron orbits in the dielectric; the changes in orientation are caused by rapid reversal in polarity of line voltage. The higher the frequency, the greater the loss [2].
DIELECTRIC LEAKAGEPower loss of a capacitor because of the leakage of current through the dielectric. Also relates to leakage resistance; the higher the leakage resistance, the lower the dielectric leakage [2].
DIELECTRIC LOSSESThe losses resulting from the heating effect on the dielectric material between conductors [10] [11].
DIELECTRIC STRENGTHThe ability of an insulator to withstand a potential difference without breaking down (usually expressed in terms of voltage) [4].
DIFFERENCE FREQUENCYSee BEAT FREQUENCY [18].
DIFFERENCE OF POTENTIALA voltage between two points [6].
DIFFERENTIAL AMPLIFIERA circuit that amplifies the difference between two input signals [8].
DIFFRACTIONThe bending of waves (as light or RF) when the waves are met with some form of obstruction [10].
DIFFUSION(1) The scattering of reflected light waves from an object, such as white paper [10]. (2) Controlled application of impurity atoms to a semiconductor substrate [14].
DIGITA symbol that represents one of the nonnegative integers smaller than the radix. For example, in decimal notation a digit is one of the characters from 0 through 9 [13].
DIGITAL COMPUTER(1) A computer in which discrete representation of data is used. (2) A computer that operates on discrete data by performing arithmetic and logic processes on these data [13].
DIODEAn electron tube containing two electrodes: a cathode and a plate [6]. (2) A two element, solid- state device made of either germanium or silicon; it is primarily used as a switching device [7] [13].
DIODE DETECTORA demodulator that uses one or more diodes to provide a rectified output with an average value that is proportional to the original modulation [12] [18].
DIPOLEA common type of half-wave antenna made from a straight piece of wire cut in half. Each half operates at a quarter wavelength of the output [10].
DIRECT CURRENTAn electric current that flows in one direction only [1].
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DIRECTIONAL ANTENNAAn antenna that radiates most effectively in only one direction [18].
DIRECTIONAL COUPLERA device that samples the energy traveling in a waveguide in one direction only [11].
DIRECTIVITYThe ability of an antenna to radiate or receive more energy in some directions than in others. The degree of sharpness of the antenna beam [10] [11] [18].
DIRECTLY HEATED CATHODEA wire, or filament, designed to emit the electrons that flow from cathode to plate. The filament is designed so that a current is passed through it; the current heats the filament to the point where electrons are emitted [6].
DIRECTORThe parasitic element of an array that reinforces energy coming from the driver element [10].
DIRECT SHORTSame as SHORT CIRCUIT [3].
DISCRETE COMPONENTSIndividual transistors, diodes, resistors, capacitors, and inductors [14].
DISCRIMINATORA circuit in which amplitude variations are derived in response to phase or frequency variations [18].
DISPERSIONThe refraction of light waves that causes the different frequencies to bend at slightly different angles [10].
DISPLACEMENT CURRENTThe current that appears to flow through a capacitor [2].
DISTILLED WATERWater that has been purified through a process of evaporation and condensation [18].
DISTORTIONAny unwanted change between an input signal and output signal [6] [8].
DISTRIBUTED CONSTANTSThe constants of inductance, capacitance, and resistance in a transmission line. They are spread along the entire length of the line and cannot be distinguished separately [10].
DISTRIBUTIVE LAWIn Boolean algebra the law which states that if a group of terms connected by like operators contains the same variable, the variable may be removed from the terms and associated with them by the appropriate sign of operation (for example, A(B + C) = AB + AC) [13].
DOMAIN THEORYA theory of magnetism based upon the electron-spin principle. Spinning electrons have a magnetic field. If more electrons spin in one direction than another, the atom is magnetized [1].
DOMINANT MODEThe easiest mode to produce in a waveguide, and the most efficient mode in terms of energy transfer [11].
DONORAn impurity that can make a semiconductor material an N-type by donating extra "free" electrons to the conduction band [7].
DONOR IMPURITYSee PENTAVALENT IMPURITY [7].
DOORKNOB TUBEAn electron tube that is similar to the acorn tube but larger. The doorknob tube is designed to operate, at high power, in the uhf frequencies [6].
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DOPINGThe process of adding impurities to semiconductor crystals to increase the number of free charges that can be moved by an external, applied voltage. Doping produces N-type or P-type material [7] [14].
DOPPLER EFFECT(1) The apparent change in frequency or pitch when a sound source moves either toward or away from a listener [10]. (2) In radar, the change in frequency of a received signal caused by the relative motion between the radar and the target [18].
DOPPLER FREQUENCYThe difference between transmitted and reflected frequencies; caused by the Doppler effect [18].
DOUBLE-MODINGIn a transmitter output tube, the abrupt and random change from one frequency to another [18].
DOUBLE NEGATIVE LAWIn Boolean algebra, the law which states that the complement of a complement is the equivalent of the original term [13].
DOUBLE RECEIVERA fine and coarse synchro receiver enclosed in a common housing with a two- shaft output (one shaft inside the other) [15].
DOUBLETAnother name for the dipole antenna [10].
DOUBLING UPThis is a type of two-equipment installation where one unit can be substituted for another in the event of failure [17].
DOWN LINKThe frequency used to transmit an amplified signal from a satellite or other craft back to earth [17].
DRIFT SPACEIn an electron, a region free of external fields in which relative electron position depends on velocity [11].
DRIVEN ARRAYAn array in which all of the elements are driven [10].
DRIVEN ELEMENTThe element of an antenna connected directly to the transmission line [10].
DRIVERThe final stage of amplification [8].
DRUM-TYPE ARMATUREAn efficient, popular type of armature designed so that the entire length of the winding is cutting the field at all times. Most wound armatures are of this type [5].
DRY-AIR SYSTEMProvides dehumidified air for electronic equipment that is moisture critical [18].
DRY CELLAn electrical cell in which the electrolyte is not a liquid. In most dry cells the electrolyte is in the form of a paste [1].
DUAL-GATE MOSFETA two-gate MOSFET in which either gate can control the conductor independently, a fact which makes this MOSFET very versatile [7].
DUAL IN-LINE PACKAGE (DIP)IC package having two parallel rows of preformed leads [14].
DUCTILEEasily drawn out (as to form filaments or wires) [4].
DUCTINGTrapping of an RF wave between two layers of the earth's atmosphere or between an atmospheric layer and the earth [18].
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DUMMY ANTENNASee DUMMY LOAD [16].
DUMMY LOADA dissipative but nonradiating device that has the impedance characteristics of an antenna or transmission line. Also called ARTIFICIAL LOAD [11] [16] [17].
DUPLEXERA radar device that switches the antenna from the transmitter to the receiver and vice versa [18].
DUTY CYCLEIn a transmitter, ratio of time on to time off [12] [18].
DYNAMIC MICROPHONEA device in which sound waves move a coil of fine wire that is mounted on the back of a diaphragm and located in the magnetic field of a permanent magnet [12].
ECHO(1) The reflection of the original sound wave as it bounces off a distant surface [10]. (2) The RF signal reflected back from a radar target [18].
ECHO BOXA resonant cavity device that is used to check the overall performance of a radar system. It receives a portion of the transmitted pulse and retransmits it back to the receiver as a slowly decaying transient [18].
ECLIPSEA condition in which the satellite is not in view or in direct line of sight with the sun. This happens when the earth is between them [17].
EDDY CURRENTInduced circulating currents in a conducting material that are caused by a varying magnetic field [2] [5].
EDDY CURRENT LOSSLosses caused by random current flowing in the core of a transformer. Power is lost in the form of heat [2].
EDISON EFFECTAlso called RICHARDSON EFFECT. The phenomenon wherein electrons emitted from a heated element within a vacuum tube will flow to a second element that is connected to a positive potential [6].
EFFECTIVE VALUESame as ROOT-MEAN-SQUARE [2].
EFFICIENCYThe ratio of output-signal power compared to the total input power, generally expressed as a percentage [1] [7].
E-FIELDElectric field that exists when a difference in electrical potential causes a stress in the dielectric between two points [11].
ELASTICITYThe ability of a substance to return to its original state [10].
ELECTRIC CURRENTThe flow of electrons [1].
ELECTRIC (E) FIELDThe field of force that is produced as a result of a voltage charge on a conductor or antenna [10] [11].
ELECTRICAL CHARGESymbol Q, q. Electric energy stored on or in an object. The negative charge is caused by an excess of electrons; the positive charge is caused by a deficiency of electrons [1].
ELECTRICAL CHEMICALThe action of converting chemical energy into electrical energy [1].
ELECTRICAL-LOCKA synchro zeroing method. This method is used only when the rotors of the synchros to be zeroed are free to turn and their leads are accessible [15].
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ELECTRICAL POWER SYSTEMProvides the necessary input power [18].
ELECTRICAL SYMBOLSGraphic symbols used to illustrate the various electrical or electronic components of a circuit [4].
ELECTRICAL ZEROA standard synchro position, with a definite set of stator voltages, that is used as the reference point for alignment of all synchro units [15].
ELECTRODEThe terminal at which electricity passes from one medium into another, such as in an electrical cell where the current leaves or returns to the electrolyte [1].
ELECTRODYNAMIC METER MOVEMENTA meter movement using fixed field coils and a moving coil; usually used in ammeters and wattmeters [3].
ELECTRODYNAMOMETERA meter using an electrodynamic movement to measure an electric current [16].
ELECTROLYSISThe process of changing the chemical composition of a material by passing an electric current through it [4] [11].
ELECTROLYTEA solution of a substance that is capable of conducting electricity. An electrolyte may be in the form of either a liquid or a paste [1].
ELECTROMAGNETAn electrically excited magnet capable of exerting mechanical force or of performing mechanical work [1].
ELECTROMAGNETICThe term describing the relationship between electricity and magnetism. A quality that combines both magnetic and electric properties [1].
ELECTROMAGNETIC FIELDThe combination of an electric (E) field and a magnetic (H) field [10].
ELECTROMAGNETIC INDUCTIONThe production of a voltage in a coil because of a change in the number of magnetic lines of force (flux linkages) passing through the coil [1] [2].
ELECTROMAGNETIC INTERFERENCEMan-made or natural interference that degrades the quality of reception of radio waves [10] [17].
ELECTROMAGNETIC RADIATIONThe radiation of radio waves into space [10].
ELECTROMAGNETISMThe generation of a magnetic field around a current-carrying conductor [2] [3].
ELECTROMOTIVE FORCE (emf)The force (voltage) that produces an electric current in a circuit [2].
ELECTRONThe elementary negative charge that revolves around the nucleus of an atom [1].
ELECTRON GUNAn electrode of a CRT that is equivalent to the cathode and control grid of conventional tubes. The electron gun produces a highly concentrated stream of electrons [6].
ELECTRON ORBITAL MOVEMENTThe movement of an electron around the nucleus of an atom [11].
ELECTRON SHELLA group of electrons which have a common energy level that forms part of the outer structure (shell) of an atom [1].
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ELECTRONIC COUNTER-COUNTERMEASURES (ECCM) CIRCUITSSee ANTIJAMMING CIRCUITS [18].
ELECTRONIC-EQUIPMENT DEHYDRATORA device that provides an alternate dry-air input in the event of failure of the central dry-air system. It may include a compressor [18].
ELECTRONIC FREQUENCY COUNTERAn instrument that counts the number of cycles (pulses) occurring during a precise time interval [18].
ELECTRONIC SCANNINGScanning in which the axis of the beam is moved, relative to the antenna axis, in a desired pattern [18].
ELECTRONIC SWITCHA circuit that causes a start-and-stop switching action by electronic means [13].
ELECTRONICS DRY-AIR BRANCHA common line for providing dry air to various electronic equipment, such as search radar, fire-control radar, and repeaters [18].
ELECTRONIC TUNINGIn a reflex klystron, changing the frequency and output power of the tube by altering the repeller voltage [11].
ELECTRON SPINThe movement of an electron around its axis [11].
ELECTROSTATICPertaining to electricity at rest, such as charges on an object (static electricity) [1].
ELECTROSTATIC DEFLECTIONThe method of deflecting an electron beam by passing it between parallel charged plates mounted inside a cathode-ray tube [6].
ELECTROSTATIC FIELDThe field of influence between two differently charged bodies [2].
ELECTROSTATIC METER MOVEMENTA meter movement that uses the electrostatic repulsion of two sets of charged plates (one fixed and the other movable). This meter movement reacts to voltage rather than to current and is used to measure high voltage [3].
ELECTROSTATIC STRESSThe force exerted on an insulator by the voltage in a conductor [4].
ELEMENT(1) A substance, in chemistry, that cannot be divided into simpler substances by any means ordinarily available [1]. (2) A part of an antenna that can be either an active radiator or a parasitic radiator [10].
ELEPHANT TRUNKDucting used for ventilation purposes [4].
ELEVATION ANGLEThe angle between the horizontal plane and the line of sight to a target or object [11] [18].
EMERGENCY POWERTemporary source of limited electrical power used upon the loss of the normal power source [18].
EMF (ELECTROMOTIVE FORCE)The force that causes electricity to flow between two points with different electrical charges or when there is a difference of potential between the two points. The unit of measurement is volts [1].
EMITTERThe element in a transistor that emits current carriers (electrons or holes) [7] [13].
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EMITTER-INJECTION MODULATORThe transistor equivalent of the cathode modulator. The gain is varied by changing the voltage on the emitter [12].
ENAMELA synthetic compound of cellulose acetate (wood pulp and magnesium). Used to insulate wire in meters, relays, and motor windings [4].
ENCAPSULATEDImbedded in solid material or enclosed in glass or metal [14].
END-FEED METHODA method in which one end of an antenna is connected through a capacitor to the final output stage of a transmitter [10].
END-FIRE ARRAYAn array in which the direction of radiation is parallel to the axis of the array [10].
ENERGYThe ability or capacity to do work [1].
EPHEMERISA table showing the precalculated position of a satellite at any given time [17].
Ep-Ip CURVEThe characteristic curve of an electron tube used to graphically depict the relationship between plate voltage (Ep) and plate current (Ip) [6].
EPITAXIAL PROCESSA method of depositing a thin, uniformly doped crystalline region (layer) on a substrate [14].
EQUATORIAL ORBITAn orbit that occurs when the plane of a satellite coincides with the plane of the earth at the equator [17].
EQUIVALENT RESISTANCE (Req)A resistance that represents the total ohmic values of a circuit component or group of circuit components. Usually drawn as a single resistor in a simplified circuit [1].
ERECTING (A GYRO)The positioning of a gyro into a desired position and the maintaining of that position [15].
ERROR DETECTORThe component in a servosystem that determines when the load has deviated from its ordered position, velocity, and so forth [15].
ERROR REDUCERThe name commonly given to the servomotor in a servosystem. So named because it reduces the error signal by providing feedback to the error detector [15].
ERROR SIGNAL(1) In servosystems, the signal whose amplitude and polarity or phase are used to correct the alignment between the controlling and the controlled elements. (2) The name given to the electrical output of a control transformer [15].
E-TRANSFORMERA special form of differential transformer employing an E-shaped core. The secondaries of the transformer are wound on the outer legs of the E, and the primary is wound on the center leg. An output voltage is developed across the secondary coils when its armature is displaced from its neutral position. This device is used as an error detector in servosystems that have limited load movements [15].
E-TYPE T-JUNCTIONA waveguide junction in which the junction arm extends from the main waveguide in the same direction as the E-field in the waveguide [11].
EUTECTIC ALLOYAn alloy that changes directly from a solid to a liquid with no plastic or semiliquid state [14].
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EUTECTIC SOLDERAn alloy of 63 percent tin and 37 percent lead. Melts at 361º F [14].
EXCITATION VOLTAGEThe supply voltage required to activate a circuit [15].
EXCITING CURRENTThe current that flows in the primary winding of a transformer when the secondary is open-circuited; it produces a magnetic flux field. Also called magnetizing current [2].
EXCLUSIVE ORA function whose output is a 1 if one and only one of the input variables is a 1 [13].
EXCLUSIVE-OR GATEA gate that produces a logic 1 output when the inputs are different, but not when they are the same [13].
EXPONENTThe numeral written in superscript (102) which indicates the power to which the base is to be raised [13].
EXPRESSIONA validated series of variables, constants, and functions that can be connected by operating symbols to describe a desired computation [13].
EXTERNALLY EXCITED METERA term used to describe meters that get their power from the circuit to which they are connected [16].
EXTERNALLY SYNCHRONIZED RADARA radar system in which timing pulses are generated by a master oscillator external to the transmitter [18].
EXTREMELY HIGH FREQUENCYThe band of frequencies from 30 gigahertz to 300 gigahertz [17].
EXTREMELY LOW FREQUENCYThe band of frequencies up to 300 hertz [17].
EXTRINSICA semiconductor in which impurities have been added to create certain charge carrier concentrations [7].
FACSIMILEThe method for transmitting and receiving still images. These images can be maps, photographs, and handwritten or printed text [17].
FACTORAny of the elements, quantities, or symbols that, when multiplied together, form a product [13].
FADINGVariations in signal strength by atmospheric conditions [101 [17].
FARADThe basic unit of capacitance. A capacitor has a capacitance of 1 farad when a voltage potential of 1 volt across it produces a charge of 1 coulomb [2].
FARADAY ROTATIONThe rotation of the plane of polarization of electromagnetic energy when it passes a substance influenced by a magnetic field that has a component in the direction of propagation [11].
FAST-TIME-CONSTANT CIRCUITDifferentiator circuit in the first video amplifier that allows only the leading edges of target returns, no matter how small or large, to be used [18].
FEEDBACKThe return of a portion of the output of a circuit to its input [8] [18].
FEEDERA transmission line that carries energy to the antenna [10].
FEEDHORNA horn radiator used to feed a reflector [18].
FEPA synthetic type of insulation (fluorinated ethylene propylene) [4].
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FERRITEA powdered and compressed ferric oxide material that has both magnetic properties and light resistance to current flow [11].
FERRITE SWITCHA ferrite device that blocks the flow of energy through a waveguide by rotating the electric field 90 degrees. The rotated energy is then reflected or absorbed [11].
FERROMAGNETIC MATERIALA highly magnetic material, such as iron, cobalt, nickel, or their alloys [1].
FERRULESThe cylindrical metallic ends of a cartridge fuse [3].
FIBER OPTICSConductors or optical waveguides that readily pass light [17].
FIBROUS BRAIDAn outer covering used to protect a conductor's insulating material. Commonly made from cotton, linen, silk, rayon, or fiberglass [4].
FIDELITY(1) The faithful reproduction of a signal. (2) The accuracy with which a system reproduces a signal at its output that faithfully maintains the essential characteristics of the input signal [7] [8] [12] [17].
FIELDThe electromagnet which furnishes the magnetic field that interacts with the armature in motors and generators [5].
FIELD-EFFECT TRANSISTOR (FET)A transistor consisting of a source, a gate, and a drain. Current flow is controlled by the transverse electric field under the gate [7].
FIELD EXCITATIONThe creation of a steady magnetic field within the field windings by the application of a dc voltage either from the generator itself or from an external source [5].
FIELD OF FORCEA term used to describe the total force exerted by an action-at-a-distance phenomenon such as gravity upon matter, electric charges acting upon electric charges, and magnetic forces acting upon other magnets or magnetic materials [1].
FILAMENTThe cathode of a thermionic tube, usually a wire or ribbon, which is heated by current passing through it [6].
FILM ICsConductive or nonconductive material deposited on a glass or ceramic substrate. Used for passive circuit components, resistors, and capacitors [14].
FILTERA selective network of resistors, capacitors, and inductors that offers comparatively little opposition to certain frequencies, while blocking or attenuating other frequencies [6] [9].
FINAL POWER AMPLIFIER (FPA)The final stage of amplification in a transmitter [12].
FIRST DETECTORSee MIXER [18].
FIXED BIASA constant value of bias voltage [6] [7] [13].
FIXED RESISTORA resistor having a definite resistance value that cannot be adjusted [1].
FIXED SPARK GAPA device used to discharge the pulse-forming network. A trigger pulse ionizes the air between two contacts to initiate the discharge [12].
FLAT LINEA transmission line that has no standing waves. This line requires no special timing devices to transfer maximum power [10].
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FLAT PACKAn IC package [14].
FLEMING VALVEAn earlier name for a diode, or a two-electrode vacuum tube used as a detector [6].
FLEXIBLE COAXIAL LINEA line made with an inner conductor that consists of flexible wire insulated from the outer conductor by a solid, continuous insulating material [10].
FLIP CHIPA monolithic IC packaging technique that eliminates the need for bonding wires [14].
FLIP-FLOPA device having two stable states and two input terminals (or types of input signals), each of which corresponds with one of the two states. The circuit remains in either state until caused to change to the other state by application of a voltage pulse. A similar bistable device with an input that allows it to act as a single-stage binary counter [13].
FLUX(1) In electrical or electromagnetic devices, a general term used to designate collectively all the electric or magnetic lines of force in a region [1]. (2) A solution that removes surface oxides from metals being soldered [2] [14].
FLUX DENSITYThe number of magnetic lines of force passing through a given area [1].
FLYWHEEL EFFECTThe ability of a resonant circuit to operate continuously because of stored energy or energy pulses [9].
FOCUSING ANODEAn electrode of a CRT that is used to focus the electrons into a tight beam [6].
FOLDED DIPOLEAn ordinary half-wave antenna (dipole) that has one or more additional conductors connected across the ends parallel to each other [10].
FORBIDDEN BANDThe energy band in an atom lying between the conduction band and the valence band. Electrons are never found in the forbidden band but may travel back and forth through it. The forbidden band determines whether a solid material will act as a conductor, a semi-conductor, or an insulator [7].
FORWARD AGCThe type of AGC that causes an amplifier to be driven towards saturation [17].
FORWARD BIASAn external voltage that is applied to a PN junction in the conducting direction so that the junction offers only minimum resistance to the flow of current. Conduction is accomplished by majority current carriers (holes in P-type material; electrons in N-type material) [7] [13] [14].
FORWARD RESISTANCEThe smaller resistance value observed when you are checking the resistance of a semiconductor [16].
FOSTER-SEELEY DISCRIMINATORA circuit that uses a double-tuned RF transformer to convert frequency variations in the received FM signal to amplitude variations. Also known as a phase-shift discriminator [12].
FOUR-ELEMENT ARRAYAn antenna array with three parasitic elements and one driven element [10].
FRAMINGThe process of synchronizing a facsimile receiver to a transmitter. This allows proper picture reproduction [17].
FREE CHARGESThose electrons that can be moved by an externally applied voltage [7].
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FREE-SPACE LOSSThe loss of energy of radio waves caused by the spreading of the wavefront as it travels from the transmitter [10].
FREQUENCY (f)(1) The number of complete cycles per second existing in any form of wave motion, such as the number of cycles per second of an alternating current [2] [10]. (2) The rate at which the vector that generates a sine wave rotates [12].
FREQUENCY COMPENSATION NETWORKCircuit modification used to improve or broaden the linearity of its frequency response [18].
FREQUENCY CUTOFFThe frequency at which the filter circuit changes from an action of rejecting the unwanted frequencies to an action of passing the desired frequencies. Conversely, the point at which the filter circuit changes from an action in which it passes the desired frequencies to an action in which it rejects the undesired frequencies [9].
FREQUENCY-DETERMINING NETWORKA circuit that provides the desired response (maximum or minimum impedance) at a specific frequency [8].
FREQUENCY DEVIATIONThe amount the frequency varies from the carrier frequency [12].
FREQUENCY DIVERSITYTransmitting (and receiving) of radio waves on two different frequencies simultaneously [10].
FREQUENCY-DIVISION MULTIPLEXINGMultiplexing that transmits and receives the full 360 degrees of each sine wave [17].
FREQUENCY METERA meter used to measure the frequency of an ac signal [3] [16].
FREQUENCY MODULATION (fm)Angle modulation in which the modulating signal causes the carrier frequency to vary. The amplitude of the modulating signal determines how far the frequency changes, and the frequency of the modulating signal determines how fast the frequency changes [12].
FREQUENCY MULTIPLIERSSpecial RF power amplifiers that multiply the input frequency [12].
FREQUENCY RESPONSEThe measure of a servo's ability to respond to various input frequencies [15].
FREQUENCY-RESPONSE CURVEA curve showing the output of an amplifier (or any other device) in terms of voltage or current plotted against frequency with a fixed-amplitude input signal [8].
FREQUENCY SCANNINGVarying the output frequency to achieve electronic scanning [18].
FREQUENCY-SHIFT KEYING (fsk)Frequency modulation somewhat similar to continuous-wave (cw) keying in AM transmitters. The carrier is shifted between two differing frequencies by opening and closing a key [12].
FREQUENCY SPECTRUMIn a radar, the entire range of frequencies contained in an RF pulse or signal [18].
FREQUENCY STABILITYRefers to the ability of an oscillator to accurately maintain its operating frequency [9].
FREQUENCY SYNTHESISA process that uses hetrodyning and frequency selection to produce a signal [17].
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FREQUENCY SYNTHESIZER(1) A frequency source of high accuracy [17]. (2) A bank of oscillators in which the outputs can be mixed in various combinations to produce a wide range of frequencies [18].
FRONT-TO-BACK RATIOThe ratio of the energy radiated in the principal direction compared to the energy radiated in the opposite direction [10].
FULL-WAVE RECTIFIERA circuit that uses both positive and negative alternations in an alternating current to produce direct current [6] [7].
FULL-WAVE VOLTAGE DOUBLERConsists of two half-wave voltage rectifiers and is used to reduce the output ripple amplitude [7].
FUNCTIONA specific purpose of an entity; its characteristic action [13].
FUNDAMENTAL FREQUENCYThe basic frequency or first harmonic frequency [10].
FUSED-ALLOY JUNCTIONSee ALLOYED-JUNCTION [7].
GAIN(1) The ratio between the amount of energy propagated from an antenna that is directional compared to the energy from the same antenna that would be propagated if the antenna were not directional [10]. (2) Any increase in the strength of a signal [18].
GAIN-BANDWIDTH PRODUCTThe number that results when the gain of a circuit is multiplied by the bandwidth of that circuit. For an operational amplifier, the gain-bandwidth product for one configuration will always equal the gain-bandwidth product for any other configuration of the same amplifier [8].
GALENAA crystalline form of lead sulfide used in early radio receivers [7].
GALVANOMETERA meter used to measure small values of current by electromagnetic or electrodynamic means [3] [4] [16].
GAMMA (γ)The emitter-to-base current ratio in a common-collector configuration [7].
GANGED TUNINGThe process used to tune two or more circuits with a single control [17].
GASOne of the three states of matter; it has no fixed form or volume [1].
GATEAs applied to logic circuitry, one of several different types of electronic devices that will provide a particular output when specified input conditions are satisfied. Also, a circuit in which a signal switches another signal on or off [13].
GATED AGCCircuit that permits automatic gain control to function only during short time intervals [18].
GATED-BEAM DETECTORAn FM demodulator that uses a special gated-beam tube to limit, detect, and amplify the received FM signal. Also known as a quadrature detector [12].
GATINGThe process of selecting those portions of a wave that exist during one or more selected time intervals or that have magnitudes between selected limits. Also, the application of a specific waveform to perform electronic switching [13].
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GENERAL PURPOSE ELECTRONIC TEST EQUIPMENT (GPETE)Test equipment that has the capability, without modification, to generate, modify, or measure a range of electronic functions required to test several equipments or systems of basically different designs [14] [16].
GENERATORA machine that converts mechanical energy to electrical energy by applying the principle of magnetic induction. A machine that produces ac or dc voltage, depending on the original design [5].
GENERATOR ENDSee INPUT END [10].
GERMANIUMA grayish-white metal having semiconductor properties [7].
GETTERAn alkali metal introduced into a vacuum tube during manufacture. It is fired after the tube has been evacuated to react chemically with (and eliminate) any remaining gases [6].
GIMBALA mechanical frame, with two perpendicular intersecting axes of rotation, used to support and furnish a gyro wheel with the necessary freedom to tilt in any direction [15].
GLOW DISCHARGEDischarge of electricity through a gas in an electron tube [18].
GRAMME-RING ARMATUREAn inefficient type of armature winding in which many of the turns are shielded from the field by its own iron ring [5].
GRAPHA pictorial presentation of the relation between two or more variable quantities, such as between an applied voltage and the current it produces in a circuit [1].
GRID BIASA constant fixed potential applied between the grid and the cathode of a vacuum tube to establish an operating point [6].
GRID CURRENTThe current that flows in the grid-to-cathode circuit of a vacuum tube [6].
GRID-GAP TUNINGA method of changing the center frequency of a resonant cavity by physically changing the distance between the cavity grids [11].
GRID-LEAK BIASA self-bias provided by a high resistance connected across the grid capacitor or between the grid and cathode [6].
GROUND(1) The point in a circuit used as a common reference point for measuring purposes. (2) To connect some point of an electrical circuit or some item of electrical equipment to earth or to the conducting medium used in lieu thereof [13].
GROUND CLUTTERUnwanted echoes, from surrounding land masses, that appear on a radar indicator [18].
GROUND-CONTROLLED APPROACHA radar system used to guide aircraft to safe landings in poor visibility conditions [18].
GROUND PLANEThe portion of a ground-plane antenna that acts as ground [10].
GROUND-PLANE ANTENNAA type of antenna that uses a ground plane as a simulated ground to produce low-angle radiation [10].
GROUND PLANESCopper planes used to minimize interference between circuits and from external sources [14].
GROUND POTENTIALZero potential with respect to the ground or earth [1].
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GROUND RANGEThe distance on the surface of the earth between a radar and its target. Equal to slant range only if both radar and target are at the same altitude [18].
GROUND REFLECTION LOSSThe loss of RF energy each time a radio wave is reflected from the earth's surface [10].
GROUND SCREENA series of conductors buried below the surface of the earth and arranged in a radial pattern. Used to reduce losses in the ground [10].
GROUND WAVESRadio waves which travel near the surface of the earth [10].
GROUPA collection of units, assemblies, subassemblies, and parts. It is a subdivision of a set or system but is not capable of performing a complete operational function [17].
GROUP VELOCITYThe forward progress velocity of a wave front in a waveguide [11].
GROWN JUNCTIONA method of mixing P-type and N-type impurities into a single crystal while the crystal is being grown [7].
GUIDANCE RADARA system which provides information that is used to guide a missile to a target [18].
GYROAbbreviation for gyroscope [15].
GYROSCOPEA mechanical device containing a spinning mass mounted so that it can assume any position in space [15].
HALF-POWER POINTA point on a waveform or radar beam that corresponds to half the power of the maximum power point [8] [9] [18].
HALF-WAVE DIPOLE ANTENNAAn antenna, consisting of two rods (1/4 wavelength each) in a single line, that radiates electromagnetic energy [10].
HALF-WAVE RECTIFIERA rectifier using only one-half of each cycle to change ac to pulsating dc [61 [7].
HALF-WAVE VOLTAGE DOUBLERTwo half-wave voltage rectifiers connected to double the input voltage [7].
HAND OVERThe operation where one earth terminal yields control to another as a satellite moves out of its area of coverage [17].
HARD-TUBE MODULATORA high-vacuum electron tube modulator that uses a driver for pulse forming [18].
HARMONICA frequency that is a whole-number multiple of a smaller base frequency [9] [10] [12] [17].
HEATERSame as a FILAMENT [6].
HEAT SHUNTA device (preferably a clip-on type) used to absorb heat and protect heat-sensitive components during soldering [4].
HEIGHT-FINDING RADARA radar that provides target altitude, range, and bearing data [18].
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HELIX(1) A spirally wound transmission line used in a traveling-wave tube to delay the forward progress of the input traveling wave [11]. (2) A large coil of wire. It acts as a coil and is used with variable inductors for impedance matching of high-power transmitters [17].
HELIX HOUSEA building at a transmitter site that contains antenna loading, coupling, and tuning circuits [17].
HENRY (H)The electromagnetic unit of inductance or mutual inductance. The inductance of a circuit is 1 henry when a current variation of 1 ampere per second induces 1 volt. In electronics, smaller units are used, such as the millihenry (mH), which is one-thousandth of a henry (H), and the microhenry (µH) which is one-millionth of a henry [2].
HERTZ (Hz)A unit of frequency equal to one cycle per second [2].
HERTZ ANTENNAA half-wave antenna that is installed some distance above ground and positioned either vertically or horizontally [10].
HETERODYNE DETECTIONThe use of an a.f. voltage to distinguish between available signals. The incoming cw signal is mixed with locally generated oscillations to give an a.f. output [12].
HETERODYNING(1) The process of mixing two frequencies across a nonlinear impedance [12]. (2) The process of mixing the incoming signal with the local oscillator frequency. This produces the two fundamentals and the sum and difference frequencies [17].
HEXADECIMALSame as SEXADECIMAL. A number system with a base of sixteen; also pertains to conditions, choices, or selections that have sixteen possible values or states [13].
HEXADECIMAL SYSTEMPertaining to the number system with a radix of sixteen. It uses the ten digits of the decimal system and the first six letters of the English alphabet [13].
H-FIELDAny space or region in which a magnetic force is exerted. The magnetic field may be produced by a current-carrying coil or conductor, by a permanent magnet, or by the earth itself [11].
HIGH FREQUENCYThe band of frequencies from 3 megahertz to 30 megahertz [17].
HIGH-FREQUENCY COMPENSATIONSee PEAKING COIL [8].
HIGH-LEVEL MODULATIONModulation produced in the plate circuit of the last radio stage of the system [12].
HIGH-PASS FILTERA filter that passes a majority of the high frequencies on to the next circuit and rejects, or attenuates, the lower frequencies. Also called a LOW-FREQUENCY DISCRIMINATOR [9].
HITS PER SCANThe number of times an RF beam strikes a target per antenna revolution [18].
HOLE FLOWIn the valence band, a process of conduction in which electrons move into holes, thereby creating other holes that appear to move toward a negative potential. (The movement of holes is opposite the movement of electrons.) [7]
HORIZONTAL AXISOn a graph, the straight line axis that is plotted from left to right [10].
HORIZONTAL-DEFLECTION PLATESA pair of parallel electrodes that moves the electron beam from side to side in a CRT [6].
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HORIZONTALLY POLARIZEDWaves radiated with their E field component parallel to the earth's surface [10].
HORIZONTAL PATTERNThe part of a radiation pattern that is radiated in all directions along the horizontal plane [10].
HORIZONTAL PLANEAn imaginary plane that is tangent (or parallel) to the earth's surface at a given location [11] [18].
HORNA funnel-shaped section of waveguide used as a termination device and as a radiating antenna [11].
HORN ANTENNASee HORN RADIATOR [18].
HORN RADIATORA tapered, tubular or rectangular microwave antenna that is widest at the open end [18].
HORSEPOWERThe English unit of power equal to work done at the rate of 550 foot-pounds per second; equal to 746 watts of electrical power [1].
HORSESHOE MAGNETA permanent magnet or electromagnet bent into the shape of a horseshoe or having a U-shape to bring the two poles near each other [1].
HOT CARRIERA carrier, which may be either a hole or an electron, that has relatively high energy with respect to the carriers normally found in majority-carrier devices [11].
HOT-CARRIER DIODEA semiconductor diode in which hot carriers are emitted from a semiconductor layer into the metal base. Also called HOT-ELECTRON DIODE. An example is the Schottky barrier diode [11].
HOT-WIRE METER MOVEMENTA meter movement that uses the expansion of a heated wire to move the pointer of a meter; measures dc or ac [3].
H-TYPE T-JUNCTIONA waveguide junction in which the junction arm is parallel to the magnetic lines of force in the main waveguide [11].
HYBRID CIRCUITA circuit where passive components (resistors, capacitors) are deposited onto a substrate made of glass, ceramic, or other insulating material. Then the active components (diodes, transistors) are attached to the substrate and connected to the passive components on the substrate with a very fine wire [7].
HYBRID ICsTwo or more integrated circuit types, or one or more integrated circuit types and discrete components on a single substrate [14].
HYBRID JUNCTIONA waveguide junction that combines two or more basic T-junctions [11].
HYBRID MIXERSee BALANCED MIXER [18].
HYBRID RINGA hybrid-waveguide junction that combines a series of E-type T-junctions in a ring configuration. When properly terminated, energy is transferred from any one branch into any two of the remaining three branches [11] [18].
HYDROMETERAn instrument used to measure specific gravity. In batteries hydrometers are used to indicate the state of charge by the specific gravity of the electrolyte [1].
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HYSTERESISThe time lag of the magnetic flux in a magnetic material behind the magnetizing force producing it. Caused by the molecular friction of the molecules trying to align themselves with the magnetic force applied to the material [2].
HYSTERESIS LOSSThe power loss in an iron-core transformer or other alternating-current device as a result of magnetic hysteresis [2].
IC SYNCHROSObsolete synchros with reverse rotation and limited torque capabilities [15].
IDEMPOTENT LAWIn Boolean algebra, combining a quantity with itself either by logical addition or logical multiplication will result in a logical sum or product that is the equivalent of the quantity (for example, A + A = A; A • A = A) [13].
IDLER FREQUENCYIn a parametric amplifier, the difference between the input signal and the pump signal frequency. Also called the LOWER-SIDEBAND FREQUENCY [11].
IF AMPLIFIERUsually a narrow-bandwidth IF amplifier that is tuned to one of the output frequencies produced by the mixer [18].
IGFETAny field-effect transistor that has an insulated gate [7].
IMAGE FREQUENCYAn undesired frequency capable of producing the desired frequency through heterodyning [17].
IMPEDANCEThe total opposition offered to the flow of an alternating current. It may consist of any combination of resistance, inductive reactance, and capacitive reactance. The symbol for impedance is Z [2] [9].
IMPLOSIONThe inward bursting of a CRT because of high vacuum. The opposite of explosion [6].
INCIDENT WAVE(1) The wave that strikes the surface of a medium. (2) The wave that travels from the sending end to the receiving end of a transmission line [10].
IN-CIRCUIT METERA meter permanently installed in a circuit; used to monitor circuit operation [3].
INCOHERENTRefers to radiation on a broad band of frequencies [17].
INDEX OF REFRACTIONThe degree of bending of an RF wave when passing from one medium to another [18].
INDICATOREquipment in radar that provides a visual presentation of target position information [18].
INDIRECTLY HEATED CATHODESame as the directly heated cathode with one exception: The hot filament raises the temperature of the sleeve around the filament; the sleeve then becomes the electron emitter [6].
INDUCED-CHANNEL MOSFETA MOSFET in which there is no actual channel between the source and the drain. This MOSFET is constructed by making the channel of the same type of material as the substrate [7].
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INDUCED CHARGEAn electrostatic charge produced on an object by the electric field that surrounds a nearby object [1].
INDUCED CURRENTCurrent caused by the relative motion between a conductor and a magnetic field [1].
INDUCED ELECTROMOTIVE FORCEThe electromotive force induced in a conductor because of the relative motion between the conductor and a magnetic field [1].
INDUCED VOLTAGESee INDUCED ELECTROMOTIVE FORCE [1].
INDUCTANCEThe property of a circuit that tends to oppose a change in the existing current flow. The symbol for inductance is L [2] [7].
INDUCTANCE BRIDGEAn ac bridge circuit used to measure an unknown value of inductance [16].
INDUCTIONThe act or process of producing voltage and current by the relative motion of a magnetic field across a conductor [1].
INDUCTION FIELDThe electromagnetic field that is produced about an antenna when current and voltage are present on the same antenna [10].
INDUCTION LOSSESThe losses that occur when the electromagnetic field around a conductor cuts through nearby metallic objects and induces a current into that object [10].
INDUCTION MOTORA simple, rugged, ac motor with desirable characteristics. The rotor is energized by transformer action (induction) from the stator. Induction motors are used more than any other type [5].
INDUCTIVE COUPLINGCoupling of two coils by means of magnetic lines of force. In transformers, coupling applied through magnetic lines of force between the primary and secondary windings [2].
INDUCTIVE REACTANCEThe opposition to the flow of an alternating current caused by the inductance of a circuit, expressed in ohms. Identified by the symbol X L [2] [9].
INERTIAThe physical tendency of a body in motion to remain in motion and a body at rest to remain at rest unless acted upon by an outside force (Newton's First Law of Motion) [15].
INFINITE(1) Extending indefinitely, endless. (2) Boundless, having no limits. (3) An incalculable number [1].
INFRALOW FREQUENCYThe band of frequencies from 300 Hz to 3,000 Hz [19].
INFRASONIC (SUBSONIC)Sounds below 15 Hz [10].
IN PHASEApplied to the condition that exists when two waves of the same frequency pass through their maximum and minimum values of like polarity at the same instant [2].
INPUTThe current, voltage, power, or driving force applied to a circuit or device [13].
INPUT ENDThe end of a two-wire transmission line that is connected to a source [10].
INPUT IMPEDANCEImpedance presented to the transmitter by the transmission line and its load [10].
INPUT/OUTPUTPertaining to either input or output or both, especially in data processors [13].
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INSTANTANEOUS AMPLITUDEThe amplitude at any given point along a sine wave at a specific instant in time [12].
INSTANTANEOUS AUTOMATIC GAIN CONTROL (IAGC)A circuit that can vary the gain of the radar receiver with each input pulse to maintain a nearly constant output peak amplitude [18].
INSTANTANEOUS VALUEThe magnitude at any particular instant when a value is continually varying with respect to time [2].
INSULATIONA material used to prevent the leakage of electricity from a conductor and to provide mechanical spacing or support as protection against accidental contact with the conductor [1] [4].
INSULATION RESISTANCEThe resistance offered by an insulating material to current leakage [4].
INSULATOR(1) Material of such low conductivity that the flow of current through it can usually be neglected. (2) A device having high electrical resistance; used for supporting or separating conductors so as to prevent undesired flow of current from the conductors to other objects [1].
INTEGRATED CIRCUIT (IC)(1) A circuit in which many elements are fabricated and interconnected by a single process (into a single chip), as opposed to a "nonintegrated" circuit in which the transistors, diodes, resistors, and other components are fabricated separately and then assembled [7]. (2) Elements inseparably associated and formed on or within a single substrate [14].
INTELLIGENCEIn communications any signal that conveys information (voice, teletypewriter, facsimile) [17].
INTENSITY (OF SOUND)The measurement of the amplitude of sound energy. Generally synonymous with loudness [10].
INTERACTION SPACEThe region in an electron tube where the electrons interact with an alternating electromagnetic field [11].
INTERCEPTThe point where two lines drawn on a graph cross each other [10].
INTERELECTRODE CAPACITANCEThe capacitance between the electrodes of an electron tube [6] [11].
INTERFERENCEAny disturbance that produces an undesirable response or degrades a signal [10].
INTERMEDIATE FREQUENCY (IF)A lower frequency to which an RF echo is converted for ease of amplification [18].
INTERMEDIATE-LEVEL MAINTENANCE (SM&R Code I)Direct support and technical assistance to user organizations. Tenders and shore-based repair facilities [14].
INTERMEDIATE POWER AMPLIFIERThe amplifier between the oscillator and final power amplifier [12].
INTERPOLESSmall auxiliary poles, placed between main field poles, whose magnetic field opposes the armature field and cancels armature reaction. Interpoles accomplish the same thing as compensating windings [5].
INTERSECTION LAWIn Boolean algebra, the law which states that if one input to an AND gate is already TRUE, then the output will depend upon the state of the other inputs only [13].
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INVERSELYInverted or reversed in position or relationship [1].
INVERTTo change a physical or logical state to its opposite state [13].
INVERTERA circuit with one input and one output. Its function is to invert or reverse the input. When the input is high, the output is low, and vice versa. The inverter is sometimes called a NOT circuit, since it produces the reverse of the input [13].
IONAn electrically charged atom or group of atoms. Negative ions have an excess of electrons; positive ions have a deficiency of electrons [1].
IONIZATION(1) The process of producing ions. (2) The electrically charged particles produced by high- energy radiation, such as light or ultraviolet rays, or by the collision of particles during thermal agitation [6] [10].
IONIZATION POINTThe potential required to ionize the gas of a gas-filled tube. Sometimes called firing potential [6].
IONIZETo make an atom or molecule of an element lose an electron, as by X-ray bombardment, and thus be converted into a positive ion. The free electron may attach itself to a neutral atom or molecule to form a negative ion [1].
IONOSPHEREThe most important region of the atmosphere extending from 31 miles to 250 miles above sea level. Contains four cloud-like layers that affect radio waves [10].
IONOSPHERIC STORMSDisturbances in the earth's magnetic field that make communications practical only at lower frequencies [10].
IRISA metal plate with an opening through which electromagnetic waves may pass. Used as an impedance-matching device in waveguides [11].
I2R LOSSSee COPPER LOSSES [11].
ISOLATIONThe prevention of unwanted interaction or leakage between components [14].
ISOMETRIC DIAGRAMA diagram showing the outline of a ship, aircraft, or equipment and the location of equipment and cable runs [4].
ISOTROPIC RADIATIONThe radiation of energy equally in all directions [10].
JUNCTION(1) The connection between two or more conductors. (2) The contact between two dissimilar metals or materials, as in a thermocouple [1].
JUNCTION BOXA box with a cover that serves the purpose of joining different runs of wire or cable and provides space for the connection and branching of the enclosed conductors [4].
JUNCTION DIODEA two-terminal device containing a single crystal of semiconducting material that ranges from P-type at one terminal to N-type at the other [7].
JUNCTION TRANSISTORA bipolar transistor constructed from interacting PN junctions. The term is used to distinguish junction transistors from other types, such as field-effect and point-contact [7].
KEEP-ALIVE CURRENTSee KEEP-ALIVE VOLTAGE [18].
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KEEP-ALIVE VOLTAGEDC voltage applied to a tr gap electrode to produce a glow discharge that allows the tube to ionize faster when the transmitter fires [18].
KEY-CLICK FILTERSFilters used in keying systems to prevent key-click interference [12].
KEY CLICKSInterference in the form of "clicks" or "thumps" caused by the sudden application or removal of power [12].
KEYED-OSCILLATOR TRANSMITTERA transmitter in which one stage is used to produce the RF pulse [18].
KEYER(1) A device that changes dc pulses to mark and space modulation for teletypewriter transmissions [17]. (2) A synchronizer [18].
KEYING RELAYSRelays used in radio transmitters where the ordinary hand key cannot accommodate the plate current without excessive arcing [12].
KILOA prefix meaning one thousand [1].
KINETIC ENERGYEnergy that a body possesses by virtue of its motion [1].
KIRCHHOFF'S LAWS(1) The algebraic sum of the current flowing toward any point in a circuit and the current flowing away from it is zero. (2) The algebraic sum of the products of the current and resistance in each of the conductors in any closed path in a network is equal to the algebraic sum of the electromotive forces in the path [1].
KLYSTRON POWER AMPLIFIERA multicavity microwave electron tube that uses velocity modulation [18].
KNEE OF THE CURVEThe point of maximum curvature of a magnetization curve. (Shaped like the knee of a leg that is bent.) [8]
LACING SHUTTLEA device upon which lacing may be wound to prevent fouling the tape or cord and to aid the lacing process. (Usually made from brass, aluminum, fiber, or plastic) [4].
LAGThe amount one wave is behind another in time; expressed in electrical degrees [2].
LAMINATED COREA core built up from thin sheets of metal insulated from each other and used in transformers [2].
LANDSConductors or runs on pcbs [14].
LAP WINDINGAn armature winding in which opposite ends of each coil are connected to adjoining segments of the commutator so that the windings overlap [5].
LARGE SCALE INTEGRATION (lsi)An integrated circuit containing 1,000 to 2,000 logic gates or up to 64,000 bits of memory [14].
LASERAn acronym for light amplification by stimulated emission of radiation [17].
LAW OF MAGNETISMLike poles repel; unlike poles attract [1].
LC CAPACITOR-INPUT FILTERThis is the most common type of filter. It is used in a power supply where output current is low and load current is relatively constant [7].
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LC CHOKE-INPUT FILTERThis filter is used in power supplies where voltage regulation is important and where the output current is relatively high and subject to varying load conditions [7].
LEADThe opposite of lag. Also a WIRE or CONNECTION [2].
LEAD-ACID CELLA cell in an ordinary storage battery in which electrodes are grids of lead containing an active material consisting of certain lead oxides that change in composition during charging and discharging. The electrodes or plates are immersed in an electrolyte of diluted sulfuric acid [1].
LEAD INDUCTANCEThe inductance of the lead wires connecting the internal components of an electron tube [11].
LEAD SHEATHA continuous jacket of lead molded around a single conductor or multiple conductor cable. Generally used to ensure conductors are protected from water or extensive moisture [4].
LEAKAGE CURRENTThe small amount of current that flows through the dielectric between the conductors of a transmission line [10].
LEAKAGE FLUXMagnetic flux lines produced by the primary winding that do not link the turns of the secondary winding [2].
LEAKAGE RESISTANCEThe electrical resistance that opposes the flow of current through the dielectric of a capacitor. The higher the leakage resistance, the slower the capacitor discharges or leaks across the dielectric [2].
LEAST SIGNIFICANT DIGIT (LSD)The LSD is the digit whose position within a given number expression has the least weighting power [13].
LEFT-HAND RULE FOR GENERATORSA rule or procedure used to determine the direction of current flow in a generator [2] [5].
LENZ'S LAWThe current induced in a circuit, caused by its motion in a magnetic field or a change in it's magnetic flux, in such a direction as to exert a mechanical force opposing the motion or to oppose the change in flux [2].
LIGHT-EMITTING DIODE (LED)A PN-junction diode that emits visible light when it is forward biased. Depending on the material used to make the diode, the light may be red, green, or amber [7].

LIGHT RAYSLight waves emitting from a source in straight lines [10].
LIMITERA device that prevents (limits) a waveform from exceeding a specified value [9].
LINEARHaving an output that varies in direct proportion to the input [6].
LINEAR IMPEDANCEAn impedance in which a change in current through a device changes in direct proportion to the voltage applied to the device [12].
LINE OF FORCEA line in an electric or magnetic field that shows the direction of the force [1].
LINE OF SIGHTStraight line from a radar antenna to a target [18].
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LINE-PULSING MODULATORCircuit that stores energy and forms pulses in the same circuit element, usually the pulse-forming network (pfn) [18].
LIN-LOG AMPLIFIERAn amplifier in which the response is linear for weak signals and logarithmic for large signals [18].
LIQUIDOne of the three states of matter. It has a definite volume but no definite form (water is a liquid) [1].
LIQUID-COOLING SYSTEMSource of cooling for high-heat producing equipments, such as microwave components, radar repeaters, and transmitters [18].
LISSAJOUS PATTERNA combined, simultaneous display of the amplitude and phase relationships of two input signals on a CRT [17].
LOAD(1) A device through which an electric current flows and which changes electrical energy into another form. (2) Power consumed by a device or circuit in performing its function [1] [13].
LOAD ENDSee OUTPUT END [10].
LOADINGSee LUMPED-IMPEDANCE TUNING [10].
LOADING EFFECTThe effect of a voltmeter upon the circuit being measured that results in an inaccurate measurement. Loading effect is minimized by using a voltmeter with an internal resistance many times higher than the resistance of the circuit being measured [3].
LOAD ISOLATORA passive attenuator in which the loss in one direction is much greater than that in the opposite direction. One example is a ferrite isolator for waveguides that allows energy to travel in only one direction [11].
LOBEAn area of greater signal strength in the transmission pattern of an antenna [10] [18].
LOCAL ACTIONA continuation of current flow within a battery cell when there is no external load. Caused by impurities in the electrode [1].
LOGARITHMIC RECEIVERReceiver that uses a linear logarithmic amplifier (lin-log) instead of a normal linear amplifier [18].
LOGICThe basic principles and applications of truth tables, interconnections of off-on circuit elements, and other factors involved in mathematical computation in automatic data processing systems and other devices [13].
LOGIC CIRCUITThe primary control information processor in digital equipment; made up of electronic gates and so named because their operation is described by simple equations of a specialized logic algebra [13].
LOGIC DIAGRAMIn computers and data processing equipment, a diagram representing the logical elements and their interconnections without necessarily expressing construction or engineering details [13].
LOGIC ELEMENTThe smallest building blocks that can be represented by operators in an appropriate system of symbolic logic. Typical logic elements are the AND-gate and the flip-flop, which can be represented as operators in a suitable symbolic logic. Also a device that performs the logic function [13].
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LOGIC INSTRUCTIONAny instruction that executes a logic operation that is defined in symbolic logic, such as AND, OR, NAND, or NOR [13].
LOGIC OPERATIONA nonarithmetical operation in a computer, such as comparing, selecting, making references, matching, sorting, and merging, where the logical YES or NO quantities are involved [13].
LOGIC SWITCHA diode matrix (See MATRIX) or other switching arrangement that is capable of directing an input signal to one of several outputs [13].
LOGIC SYMBOLA symbol used to represent a logic element graphically. Also a symbol used to represent a logic operator [13].
LONGITUDINAL WAVESThose waves in which the disturbance (back and forth motion) takes place in the direction of propagation. Sometimes called compression waves [10].
LONG-WIRE ANTENNAAn antenna that is a wavelength or more long at its operating frequency [10].
LOOPA curved conductor that connects the ends of a coaxial cable or other transmission line and projects into a waveguide or resonant cavity for the purpose of injecting or extracting energy [10] [11].
LOOSE COUPLINGInefficient coupling of energy from one circuit to another that is desirable in some applications. Also called weak coupling [11].
LOWER-FREQUENCY CUTOFFThe lowest frequency a circuit will pass [9].
LOWER SIDEBANDAll difference frequencies below that of the carrier [12].
LOWEST USABLE FREQUENCYThe minimum operating frequency that can be used for communications between two points [10].
LOW FREQUENCYThe band of frequencies from 30 kHz to 300 kHz [17].
LOW-LEVEL MODULATIONModulation produced in an earlier stage than the final [12].
LOW-NOISE AMPLIFIERSee PREAMPLIFIER [18].
LOW-PASS FILTERA filter that passes a majority of the low frequencies on to the next circuit and rejects, or attenuates, the higher frequencies. Also called a high-frequency discriminator [9] [12].
LSDSee LEAST SIGNIFICANT DIGIT [13].
LUMPED CONSTANTSThe properties of inductance, capacitance, and resistance in a transmission line [10].
LUMPED IMPEDANCE TUNINGThe insertion of an inductor or capacitor in series with an antenna to electrically lengthen or shorten the antenna [10].
MACHINE KEYINGA method of cw keying using punched tape or other mechanical means to key a transmitter [12].
MAGIC TSee BALANCED MIXER [18].
MAGIC-T JUNCTIONA combination of H-type and E-type T-junctions [11].
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MAGNET WIREWire coated with an enamel insulation and used in coils, relays, transformers, motor windings, and so forth [4].
MAGNETIC AMPLIFIERAn electromagnetic device that uses one or more saturable reactors to obtain a large power gain. This device is used in servosystems requiring large amounts of power to move heavy loads [8] [15].
MAGNETIC FIELD(1) The region in which the magnetic forces created by a permanent magnet or by a current-carrying conductor or coil can be detected [1] [2]. (2) The field that is produced when current flows through a conductor or antenna [10] [11].
MAGNETIC INDUCTIONGenerating a voltage in a circuit by the creation of relative motion between a magnetic field and the circuit. The relative motion can be the result of physical movement or the rise and fall of a magnetic field created by a changing current [5].
MAGNETIC LINES OF FORCEImaginary lines used for convenience to designate the direction in which magnetic forces are acting as a result of magnetomotive force [2].
MAGNETIC MICROPHONEA microphone in which the sound waves vibrate a moving armature. The armature consists of a coil wound on the armature and located between the pole pieces of a permanent magnet. The armature is mechanically linked to the diaphragm [12].
MAGNETIC POLESThe section of a magnet where the flux lines are concentrated; also where they enter and leave the magnet [1].
MAGNETIC TRIP ELEMENTA circuit breaker trip element that uses the increasing magnetic attraction of a coil with increased current to open the circuit [3].
MAGNETISMThe property possessed by certain materials by which these materials can exert mechanical force on neighboring masses of magnetic materials and can cause currents to be induced in conducting bodies moving relative to the magnetized bodies [1].
MAGNETRON OSCILLATORAn electron tube that provides a high power output. Theory of operation is based on interaction of electrons with the crossed electric and magnetic fields in a resonant cavity [18].
MAINTENANCEWork done to correct, reduce, or counteract wear, failure, and damage to equipment [16].
MAJOR LOBEThe lobe in which the greatest amount of radiation occurs [10].
MAJORITY CARRIERSThe mobile charge carriers (hole or electron) which are predominate in a semiconductor material; for example, electrons in an N-type region [7].
MARCONI ANTENNAA quarter-wave antenna that is operated with one end grounded and is positioned perpendicular to the earth [10].
MARKAn interval during which a signal is present. Also the presence of an RF signal in cw keying. The key-closed condition (presence of data) in communications systems [12].
MARKINGThe state where a circuit is closed and current flows in teletypewriter operation [17].
MASKA device used to deposit materials on a substrate in the desired pattern [14].
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MASTER OSCILLATORIn a transmitter, the oscillator that establishes the carrier frequency of the output [18].
MASTER OSCILLATOR POWER AMPLIFIER (MOPA)A transmitter in which the oscillator is isolated from the antenna by a power amplifier [12].
MATRIXIn computers, a logic network in the form of an array of input leads and output leads with logic elements connected at some of their intersections [13].
MATTERAny physical entity that possesses mass [1].
MAXIMUM USABLE FREQUENCYMaximum frequency that can be used for communications between two locations for a given time of day and a given angle of incidence [10].
MEASURE (METROLOGY AUTOMATED SYSTEM FOR UNIFORM RECALL AND REPORTING)The Navy data processing system designed to provide a standardized system for the recall, scheduling, and documenting of test equipment into calibration facilities [16].
MECHANICAL-ROTATION FREQUENCYThe speed in revolutions per minute of armatures in electric motors and engine-driven generators; blade speed in turbines [16].
MECHANICAL SCANNINGThe reflector, its feed source, or the entire antenna is moved in a desired pattern [18].
MECHANIZATIONUsing electric or electro-mechanical switches to represent logic circuits (AND, OR, NOT, NOR, NAND) [13].
MEDIUMThe vehicle through which a wave travels from one point to the next. Air, water, and wood are examples [10].
MEDIUM ALTITUDE ORBITAn orbit from 2,000 to 12,000 miles above the earth. The rotation rate of the earth and satellite are quite different, and the satellite moves quickly across the sky [17].
MEDIUM FREQUENCYThe band of frequencies from 300 kHz to 3 MHz [17].
MEGAA prefix meaning one million; also MEG [1].
MEGGERCommon name for a megohmmeter [3] [16].
MEGOHMMETERA meter that measures very large values of resistance; usually used to check for insulation breakdown in wires [3].
METALLIC ARMORA protective covering for wires or cables. Made as a woven wire braid, metal tape, or interlocking metal cover. Made from steel, copper, bronze, or aluminum [4].
METALLIC, INSULATORA shorted quarter-wave section of transmission line [11].
METALLIC RECTIFIERAlso known as a DRY-DISC RECTIFIER. A metal-to-semiconductor, large- area, contact device in which a semiconductor is sandwiched between two metal plates. This asymmetrical construction permits current to flow more readily in one direction than the other [7].
METAL-OXIDE SEMICONDUCTOR FIELD-EFFECT TRANSISTORSee MOSFET [7].
METERA device used to measure a specific quantity, such as current, voltage, or frequency [3].
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METER MOVEMENTThe part of the meter that moves to indicate some value [3] [16].
METER SHUNTA resistor placed in parallel with the meter terminals; used to provide increased range capability [16].
MHOUnit of conductance; the reciprocal of the ohm [1].
MICROA prefix meaning one-millionth [1].
MICROCIRCUITA small circuit having high equivalent-circuit-element density, which is considered as a single part composed of interconnected elements on or within a single substrate to perform an electronic-circuit function [14].
MICROCIRCUIT MODULEAn assembly of microcircuits or a combination of microcircuits and discrete components that perform one or more distinct functions [14].
MICROELECTRONICSThe solid-state concept of electronics in which compact semiconductor materials are designed to function as an entire circuit or subassembly rather than as circuit components [7] [14].
MICROPHONEAn energy converter that changes sound energy into electrical energy [12].
MICROWAVE REGIONThe portion of the electromagnetic spectrum from 1,000 MHz to 100,000 MHz [11].
MILThe diameter of a conductor equal to 1/1000 (.001) inch [4].
MIL FOOTA unit of measurement for conductors (diameter of 1 mil, 1 foot in length.) [4].
MILITARY SPECIFICATIONS (MIL-SPEC)Technical requirements and standards adopted by the Department of Defense that must be met by vendors selling materials to DOD [4].
MILITARY STANDARDS (MILSTD)Standards of performance for components or equipment that must be met to be acceptable for military systems [14].
MILLIA prefix meaning one-thousandth [1].
MINIATURE ELECTRONICSModules, packages, pcbs, and so forth, composed exclusively of discrete components [14].
MINIMUM DISCERNIBLE SIGNAL (MDS)The weakest input signal that produces a usable signal at the output of a receiver. The weaker the input signal, the more sensitive the receiver [18].
MINORITY CARRIERSEither electrons or holes, whichever is the less dominant carrier in a semiconductor device. In P-type semiconductors, electrons are the minority carriers; in N-type semiconductors, the holes are the minority carriers [7].
MINORITY CURRENTA very small current that passes through the base-to-collector junction when this junction is reverse biased [7].
MINOR LOBEThe lobe in which the radiation intensity is less than that of a major lobe [10].
MIXERIn radar, a circuit that combines the received RF signal with a local-oscillator signal to effectively convert the received signal to a lower IF frequency signal [18].
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MODE SHIFTINGIn a magnetron, the inadvertent shifting from one mode to another during a pulse [18].
MODE SKIPPINGOperation in which the magnetron fires randomly, rather than firing on each successive pulse as desired [18].
MODIFIED TRANSISTOR OUTLINE (TO)An IC package resembling a transistor [14].
MODULAR CIRCUITRYA technique where printed circuit boards are stacked and connected together to form a module [7].
MODULAR PACKAGINGCircuit assemblies or subassemblies packaged to be easily removed for maintenance or repair [14].
MODULATED WAVEA complex wave consisting of a carrier and a modulating wave that is transmitted through space [12].
MODULATING WAVEAn information wave representing intelligence [12].
MODULATIONThe process of impressing intelligence upon a transmission medium, such as radio waves [12].
MODULATION FACTOR (M)An indication of relative magnitudes of the RF carrier and the modulating signal [12].
MODULATION INDEXThe ratio of frequency deviation to the frequency of the modulating signal [12].
MODULATOR(1) A device that produces modulation; that is, a device that varies the amplitude, frequency, or phase of an ac signal [11] [12]. (2) A circuit used in servosystems to convert a dc signal to an ac signal. The output ac signal is a sine wave at the frequency of the ac reference voltage. The amplitude of the output is directly related to the amplitude of the dc input. The circuit's function is opposite to that of a DEMODULATOR [15]. (3) In radar, it produces a high-voltage pulse that turns the transmitter on and off [18].
MODULATOR SWITCHING DEVICEControls the on (discharge) and off (charge) time of the modulator [18].
MODULEA circuit or portion of a circuit packaged as a removable unit. A separable unit in a packaging scheme displaying regularity of dimensions [14].
MOISTURE LAPSEAbnormal variation of moisture content at different altitudes because of high moisture located just above large bodies of water [18].
MONOLITHIC CIRCUITA circuit where all elements (resistors, transistors, and so forth) associated with the circuit are fabricated inseparably within a continuous piece of material (called the substrate), usually silicon [7].
MONOLITHIC ICICs that are formed completely within a semiconductor substrate. Silicon chips [14].
MONOPULSE (SIMULTANEOUS) LOBINGA radar receiving method using two or more (usually four) partially overlapping lobes. Sum and difference locate the target with aspect to the axis of the antenna [18].
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MONOPULSE RADARA radar that gets the range, bearing, and elevation position data of a target from a single pulse [18].
MONOPULSE RECEIVERSee MONOPULSE RADAR [18].
MONOSTABLE MULTIVIBRATORA multivibrator that has one steady state. A signal (trigger) must be applied to cause change of states [9].
MOSFETA semiconductor device that contains diffused source and drain regions on either side of a P- or N-channel area. Also contains a gate insulated from the channel area by silicon-oxide. Operates in either the depletion or the enhancement mode [7].
MOST SIGNIFICANT DIGIT (MSD)The MSD is the digit whose position within a given number expression has the greatest weighting power [13].
MOTORA machine that converts electrical energy to mechanical energy. It is activated by ac or dc voltage, depending on the design [5].
MOTOR LOADAny device driven by a motor. Typical loads are drills, saws, water pumps, rotating antennas, generators, and so forth. The speed and power capabilities of a motor must be matched to the speed and power capabilities of the motor load [5].
MOTOR REACTIONThe force created by generator armature current that tends to oppose the normal rotation of the armature [5].
MOTOR STARTERSLarge resistive devices placed in series with dc motor armatures to prevent the armature from drawing excessive current until armature speed develops counter emf. The resistance is gradually removed from the circuit either automatically or manually as motor speed increases [5].
MOVING-IRON METER MOVEMENTSame as MOVING-VANE METER MOVEMENT [3].
MOVING TARGET INDICATORA device that limits the display of radar information to moving targets [18].
MOVING-VANE METER MOVEMENTA meter movement that uses the magnetic repulsion of the like poles created in two iron vanes by current through a coil of wire; most commonly used movement for ac meters [3].
MSDSee MOST SIGNIFICANT DIGIT [13].
MTDSAn abbreviation for the marine tactical data system [17].
MUSymbol for amplification factor [6] [7].
MULTICONDUCTORMore than one conductor, as in a cable [4].
MULTICOUPLERSCouplers that patch receivers or transmitters to antennas. They also filter out harmonics and spurious responses and impedance-match the equipment [17].
MULTIELECTRODE TUBEAn electron tube normally classified according to its number of electrodes (the multielectrode tube contains more than three electrodes) [6].
MULTIELEMENT ARRAYAn array that consists of one or more arrays and is classified as to directivity [10].
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MULTIELEMENT PARASITIC ARRAYAn array that contains two or more parasitic elements and a driven element [10].
MULTILOOP SERVOSYSTEMA servosystem that contains more than one servo loop; each loop is designed to perform its own function [15].
MULTIMETERA single meter combining the functions of an ammeter, a voltmeter, and an ohmmeter [3].
MULTIPATHThe multiple paths a radio wave may follow between transmitter and receiver [10].
MULTIPHASESee POLYPHASE [5].
MULTIPLICATION FACTORThe number of times an input frequency is multiplied [12].
MULTIPLEXINGA method for simultaneous transmission of two or more signals over a common carrier wave [17].
MULTISPEED SYNCHRO SYSTEMSSystems that transmit data at different transmission speeds; for example, dual-speed and tri-speed synchro systems [15].
MULTIUNIT TUBEAn electron tube containing two or more units within the same envelope. The multiunit tube is capable of operating as a single-unit tube, or each unit can operate as a separate tube [6].
MULTIVIBRATORA form of relaxation oscillator which comprises two stages that are coupled so that the input of one is derived from the output of the other [9] [13].
MULTIVIBRATOR MODULATORAn astable multivibrator used to provide frequency modulation. The modulating af voltage is inserted in series with the base return of the multivibrator transistors to produce the frequency modulation [12].
MUTUAL FLUXThe total flux in the core of a transformer that is common to both the primary and secondary windings. The flux links both windings [2].