RHOMBIC ANTENNAA diamond-shaped antenna used widely for long-distance, high-frequency
transmission and reception.
RIGID COAXIAL LINEA coxial line consisting of a central, insulated wire (inner conductor)
mounted inside a tubular outer conductor.
SCATTER ANGLEThe angle at which the receiving antenna must be aimed to capture the scattered
energy of tropospheric scatter.
SELF-INDUCTIONThe phenomenon caused by the expanding and collapsing fields of an electron
which encircles other electrons and retards the movement of the encircled electrons.
SELF-LUMINOUS BODIESObjects that produce their own light.
SENDING ENDSee INPUT END.
SERIES RESONANT CIRCUITA circuit that acts as a low impedance at resonance.
SHIELDED PAIRA line consisting of parallel conductors separated from each other and surrounded
by a solid dielectric.
SHORT-CIRCUITED LINEA transmission line that has a terminating impedance equal to 0.
SINKSee OUTPUT END.
SKIN EFFECTThe flow of ac current near the surface of a conductor at rf frequencies.
SKIP DISTANCEThe distance from a transmitter to the point where the sky wave is first returned to
SKIP ZONEA zone of silence between the point where the ground wave becomes too weak for
reception and the point where the sky wave is first returned to earth.
SKY WAVESRadio waves reflected back to earth from the ionosphere.
SONICPertaining to sounds capable of being heard by the human ear.
SOURCE(1) The object that produces waves or disturbance. (2) The name given to the end of a two-
wire transmission line that is connected to a source.
SPACE DIVERSITYReception of radio waves by two or more antennas spaced some distance apart.
SPACE WAVEA radio wave that travels directly from the transmitter to the receiver and remains in
SPECTRUM(1) The entire range of electromagnetic waves. (2) VISIBLE. The range of
electromagnetic waves that stimulate the sense of sight. (3) ELECTROMAGNETIC. The entire
range of electromagnetic waves arranged in order of their frequencies.
SPORADIC E LAYERIrregular cloud-like patches of unusually high ionization. Often forms at
heights near the normal E layer.
SPREADERInsulator used with transmission lines and antennas to keep the parallel wires separated.