"A",
"B",
"C",
"D",
"E",
"F",
"G",
"H",
"I",
"J",
"K",
"L",
"M",
"N",
"O",
"P",
"Q",
"R",
"S",
"T",
"U",
"V",
"W",
"X",
"Y",
"Z"
CAPTURE BEAM: A wide beam incorporated in
capture transmitters of beam rider (command guided) missile systems to facilitate gaining initial control of a missile immediately after launch. Upon capture, the system then centers the missile in the narrow guidance beam.
CAPTURE TRANSMITTER: A transmitter employing a wide beam antenna to gain initial control of in-flight
missile for the purpose of centering the missile in the guidance transmitter antenna beam. See also Capture Beam.
CARRIER FREQUENCY: The frequency of an unmodulated transmitter output. The basic radio
frequency of the wave upon which modulations are impressed. Also called "Carrier" or fc.
CARRIER POWER: (of a radio transmitter): 1. The average power supplied to the antenna transmission
line by a transmitter during one radio frequency cycle taken under the condition of no modulation. 2. The
average unmodulated power supplied to a transmission line.
CASSEGRAIN ANTENNA: An antenna in which the feed radiator is mounted at or near the surface of a concave
main reflector and is aimed at a convex secondary reflector slightly inside the focus of the main reflector.
CAVITY: A space enclosed by a conducting surface used as a resonant circuit at microwave frequencies. Cavity
space geometry determines the resonant frequency. A storage area for oscillating electromagnetic energy.
C-BAND: A frequency band between 4 GHz and 6 GHz used in satellite communications. NOTE; "Letter designators of radio frequency bands are imprecise, deprecated, and legally obsolete."
CENTER FREQUENCY: The tuned or operating frequency. Also referred to as center operating frequency. In
frequency diversity systems, the midband frequency of the operating range. See also Carrier Frequency.
CHAFF Ribbon-like pieces of metallic materials or metallized plastic which are dispensed by aircraft or ships to mask or screen other "targets". The radar reflections off the chaff may cause a tracking radar to break lock on the target. The foil materials are generally cut into small pieces for which the size is dependent upon the radar interrogation frequency (approximately 1/2 wave length of the victim radar frequency). Being this length, chaff acts as a resonant dipole and
reflects much of the energy back to the radar. Also see rainbow, rope, stream chaff, and window.
CHANNEL: A frequency or band of frequencies. In guided missile systems, an assigned center frequency and a fixed bandwidth around it. Designates operating frequency of track radars and frequency/code assignments of X-band CW illuminators.
CHIRP: A pulse compression technique which uses frequency modulation (usually linear) on pulse transmission.
CHIRP RADAR: See PC.
CIRCULARLY POLARIZED JAMMING: The techniques of radiating jamming energy in both planes of
polarization simultaneously. With this method, there is a loss of 3 dB of effective power in either linear plane, and
substantial loss if the opposite sense of circular polarization is used (i.e. left vs right).
CLUTTER: Confusing, unwanted echoes that interfere with the observation of desired signals on a
radar indicator.
CLUTTER, RADAR: Undesired radar returns or
echoes resulting from man-made or natural objects including
chaff, sea, ground, and rain, which interfere with normal radar
system observations. The figure illustrates a target being masked by ground clutter.
CO-CHANNEL: The term is used to indicate that two (or more) equipments are operating on the same frequency.
COHERENT: A definite phase relationship between two energy waves, such as transmitted frequency
and reference frequency. Two signals that have a set (usually fixed) phase relationship.
Next set of "C" Definitions and terms.
