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E

E-FIELD

Electric field that exists when a difference in electrical potential causes a stress in the dielectric between two points [11].


E-TRANSFORMER

A 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-JUNCTION

A waveguide junction in which the junction arm extends from the main
waveguide in the same direction as the E-field in the waveguide [11].


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 BOX

A 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].


ECLIPSE

A 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 CURRENT

Induced circulating currents in a conducting material that are caused by a varying magnetic field [2] [5].


EDDY CURRENT LOSS

Losses caused by random current flowing in the core of a transformer. Power
is lost in the form of heat [2].


EDISON EFFECT

Also 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 VALUE

Same as ROOT-MEAN-SQUARE [2].

EFFICIENCY

The ratio of output-signal power compared to the total input power, generally expressed as a percentage [1] [7].


ELASTICITY

The ability of a substance to return to its original state [10].

ELECTRIC (E) FIELD

The field of force that is produced as a result of a voltage charge on a conductor or antenna [10] [11].


ELECTRIC CURRENT

The flow of electrons [1].

ELECTRICAL CHARGE

Symbol 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 CHEMICAL

The action of converting chemical energy into electrical energy [1].

ELECTRICAL POWER SYSTEM

Provides the necessary input power [18].

ELECTRICAL SYMBOLS

Graphic symbols used to illustrate the various electrical or electronic
components of a circuit [4].


ELECTRICAL ZERO

A standard synchro position, with a definite set of stator voltages, that is used as the reference point for alignment of all synchro units [15].


ELECTRICAL-LOCK

A 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].


ELECTRODE

The 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 MOVEMENT

A meter movement using fixed field coils and a moving coil; usually used in ammeters and wattmeters [3].


ELECTRODYNAMOMETER

A meter using an electrodynamic movement to measure an electric
current [16].


ELECTROLYSIS

The process of changing the chemical composition of a material by passing an electric current through it [4] [11].


ELECTROLYTE

A 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].


ELECTROMAGNET

An electrically excited magnet capable of exerting mechanical force or of
performing mechanical work [1].


ELECTROMAGNETIC

The term describing the relationship between electricity and magnetism. A
quality that combines both magnetic and electric properties [1].


ELECTROMAGNETIC FIELD

The combination of an electric (E) field and a magnetic (H) field [10].

ELECTROMAGNETIC INDUCTION

The 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 INTERFERENCE

Man-made or natural interference that degrades the quality of reception of radio waves [10] [17].


ELECTROMAGNETIC RADIATION

The radiation of radio waves into space [10].

ELECTROMAGNETISM

The generation of a magnetic field around a current-carrying conductor [2]
[3].


ELECTROMOTIVE FORCE

The force (voltage) that produces an electric current in a circuit [2].

ELECTRON

The elementary negative charge that revolves around the nucleus of an atom [1].

ELECTRON GUN

An 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 MOVEMENT

The movement of an electron around the nucleus of an atom [11].


ELECTRON SHELL

A group of electrons which have a common energy level that forms part of the
outer structure (shell) of an atom [1].


ELECTRON SPIN

The movement of an electron around its axis [11].

ELECTRONIC COUNTER-COUNTERMEASURES (ECCM) CIRCUITS

See ANTIJAMMING CIRCUITS [18].


ELECTRONIC FREQUENCY COUNTER

An instrument that counts the number of cycles (pulses) occurring during a precise time interval [18].


ELECTRONIC SCANNING

Scanning in which the axis of the beam is moved, relative to the antenna
axis, in a desired pattern [18].


ELECTRONIC SWITCH

A circuit that causes a start-and-stop switching action by electronic means
[13].


ELECTRONIC TUNING

In a reflex klystron, changing the frequency and output power of the tube by
altering the repeller voltage [11].


ELECTRONIC-EQUIPMENT DEHYDRATOR

A 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].


ELECTRONICS DRY-AIR BRANCH

A common line for providing dry air to various electronic equipment, such as search radar, fire-control radar, and repeaters [18].


ELECTROSTATIC

Pertaining to electricity at rest, such as charges on an object (static electricity) [1].

ELECTROSTATIC DEFLECTION

The method of deflecting an electron beam by passing it between parallel charged plates mounted inside a cathode-ray tube [6].


ELECTROSTATIC FIELD

The field of influence between two differently charged bodies [2].

ELECTROSTATIC METER MOVEMENT

A 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 STRESS

The 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 TRUNK

Ducting used for ventilation purposes [4].

ELEVATION ANGLE

The angle between the horizontal plane and the line of sight to a target or object [11] [18].


EMERGENCY POWER

Temporary 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].


EMITTER

The element in a transistor that emits current carriers (electrons or holes) [7] [13].

EMITTER-INJECTION MODULATOR

The transistor equivalent of the cathode modulator. The gain is varied by changing the voltage on the emitter [12].


ENAMEL

A synthetic compound of cellulose acetate (wood pulp and magnesium). Used to insulate wire in meters, relays, and motor windings [4].


ENCAPSULATED

Imbedded in solid material or enclosed in glass or metal [14].

END-FEED METHOD

A method in which one end of an antenna is connected through a capacitor to the final output stage of a transmitter [10].


END-FIRE ARRAY

An array in which the direction of radiation is parallel to the axis of the array [10].

ENERGY

The ability or capacity to do work [1].

Ep-Ip CURVE

The characteristic curve of an electron tube used to graphically depict the relationship between plate voltage (Ep) and plate current (Ip) [6].


EPHEMERIS

A table showing the precalculated position of a satellite at any given time [17].

EPITAXIAL PROCESS

A method of depositing a thin, uniformly doped crystalline region (layer) on a
substrate [14].


EQUATORIAL ORBIT

An orbit that occurs when the plane of a satellite coincides with the plane of the earth at the equator [17].


EQUIVALENT RESISTANCE

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

The positioning of a gyro into a desired position and the maintaining of that
position [15].


ERROR DETECTOR

The component in a servosystem that determines when the load has deviated from its ordered position, velocity, and so forth [15].


ERROR REDUCER

The 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].


EUTECTIC ALLOY

An alloy that changes directly from a solid to a liquid with no plastic or semiliquid state [14].


EUTECTIC SOLDER

An alloy of 63 percent tin and 37 percent lead. Melts at 361o F [14].

EXCITATION VOLTAGE

The supply voltage required to activate a circuit [15].

EXCITING CURRENT

The 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 OR

A function whose output is a 1 if one and only one of the input variables is a 1 [13].

EXCLUSIVE-OR GATE

A gate that produces a logic 1 output when the inputs are different, but not
when they are the same [13].


EXPONENT

The numeral written in superscript (102) which indicates the power to which the base is to be raised [13].


EXPRESSION

A validated series of variables, constants, and functions that can be connected by operating symbols to describe a desired computation [13].


EXTERNALLY EXCITED METER

A term used to describe meters that get their power from the circuit to which they are connected [16].


EXTERNALLY SYNCHRONIZED RADAR

A radar system in which timing pulses are generated by a master oscillator external to the transmitter [18].


EXTREMELY HIGH FREQUENCY

The band of frequencies from 30 gigahertz to 300 gigahertz [17].

EXTREMELY LOW FREQUENCY

The band of frequencies up to 300 hertz [17].

EXTRINSIC

A semiconductor in which impurities have been added to create certain charge carrier concentrations [7].



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