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AMPLITUDE—The 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 DISTORTION—Distortion 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 MODULATION—Any method of varying the amplitude of an electromagnetic carrier
frequency in accordance with the intelligence to be transmitted [12].
AMPLITUDE STABILITY—Amplitude stability refers to the ability of the oscillator to maintain a
constant amplitude in the output waveform [9].
AND CIRCUIT—See 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 MODULATION—Modulation in which the angle of a sine-wave carrier is varied by a modulating
wave [12].
ANGLE OF INCIDENCE—The angle between the incident wave and the normal [10].
ANGLE OF INCLINATION—The angular difference between the equatorial plane of the earth and the
plane of orbit of the satellite [17].
ANGLE OF REFLECTION—The angle between the reflected wave and the normal [10].
ANGLE OF REFRACTION—The angle between the normal and the path of a wave through the second
medium [10].
ANGSTROM UNIT—The unit used to define the wavelength of light waves [10].
ANISOTROPIC—The 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].
ANTENNA—A 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 WIDTH—Width of a radar beam measured between half-power points [18].
ANTENNA COUPLER—A device used for impedance matching between an antenna and a transmitter or
receiver [17].
ANTENNA SYSTEM—Routes RF energy from the transmitter, radiates the energy into space, receives
echoes, and routes the echoes to the receiver [18].
ANTIJAMMING CIRCUIT—An electronic circuit used to minimize the effects of enemy
countermeasures, thereby permitting radar echoes to be visible on the indicator [18].
