AI-5
HYBRID RING—A circular waveguide arrangement with four branches. When properly terminated,
energy is transferred from any one branch into any two of the remaining three branches.
HYBRID MIXER—See Balanced Mixer.
IF AMPLIFIER—Usually a narrow-bandwidth IF amplifier that is tuned to one of the output
frequencies produced by the mixer.
INDEX OF REFRACTION—The degree of bending of an rf wave when passing from one medium to
another.
INDICATOR—Equipment that provides a visual presentation of target position information.
INSTANTANEOUS AUTOMATIC GAIN CONTROL (IAGC)—Circuit that can vary the gain of the
radar receiver with each input pulse to maintain the output peak amplitude nearly constant.
INTERMEDIATE FREQUENCY (IF)—A lower frequency to which an rf echo is converted for ease of
amplification.
KEEP-ALIVE CURRENT—See Keep-Alive Voltage.
KEEP-ALIVE VOLTAGE—Dc voltage applied to a tr gap electrode to produce a glow discharge that
allows the tube to ionize faster when the transmitter fires.
KEYED-OSCILLATOR TRANSMITTER—A transmitter in which one stage is used to produce the rf
pulse.
KEYER—See Synchronizer.
KLYSTRON POWER AMPLIFIER—Multicavity microwave electron tube that uses velocity
modulation.
LIN-LOG AMPLIFIER—Amplifier in which the response is linear for weak signals and logarithmic for
large signals.
LINE OF SIGHT—Straight line from a radar antenna to a target.
LINE-PULSING MODULATOR—Circuit that stores energy and forms pulses in the same circuit
element, usually the pulse-forming network (pfn).
LIQUID-COOLING SYSTEM—Source of cooling for high-heat producing equipments, such as
microwave components, radar repeaters, and transmitters.
LOBE—An area of greater signal strength in the transmission pattern of an antenna.
LOGARITHMIC RECEIVER—Receiver that uses a linear logarithmic amplifier (lin-log) instead of a
normal linear amplifier.
LOW-NOISE AMPLIFIER—See Preamplifier.
MAGIC T—See Balanced Mixer.
MAGNETRON OSCILLATOR—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.
