SCANNINGSystematic movement of a radar beam to cover a definite pattern or area in space.
SEA CLUTTERUnwanted echoes from the irregular surface of the sea that appear on a radar
SEARCH RADAR SYSTEMEarly-warning device that searches a fixed volume of space.
SECOND DETECTOR DEMODULATORThe part of the receiver that separates the audio or video
component from the modulated intermediate frequency.
SECOND-SWEEP ECHOESSee Ambiguous Returns.
SECONDARY LOOPIn a cooling system, the loop that transfers the heat from the heat source
(electronic equipment) to the primary loop; usually distilled water.
SELF-SYNCHRONIZED RADARA type of radar in which the timing pulses are generated within
SENSITIVITY TIME CONTROL (STC)A circuit that varies the gain of a receiver as a function of
SERIES-CONNECTED DUPLEXERConfiguration in which the tr spark gap is connected in series
in one leg of the transmission line one-half wavelength away from the T- junction.
SHADOWA dead spot (minimum radiation) caused by the physical obstruction of transmitted waves
by a feed horn.
SINGLE-ENDED MIXERSee Unbalanced Crystal Mixer.
SINGLE, STATIONARY-LOBE SCANNING SYSTEMAntenna (with a single, stationary beam)
that is rotated to obtain 360-degree coverage.
SLANT RANGESee Range.
SPECTRUM ANALYZERA test instrument that provides a visual display of the frequency
distribution of a transmitter output.
SPHERICAL WAVEFRONTSWaves of energy that spread out in concentric circles.
STABILITYIn a magnetron, the ability to maintain normal operating characteristics.
STATUTE MILEI5,280 ft.
STUBA short section of transmission line connected in parallel with the main transmission line.
SCINTILLATIONApparent change in target reflectivity. Motion of the target causes radar pulses to
bounce off different parts of the target, such as fuselage and wingtip.
SUPERHETERODYNE RECEIVERA type of receiver that uses a mixer to convert the rf echo to an
IF signal for amplification.
SUPPORT SYSTEMFor a radar, a system that provides an auxiliary input, such as dry air, electrical
power, or liquid cooling.
SYMMETRICAL MULTIVIBRATORCircuit that generates square waves.