________________________________________________________________________Glossary
sonic
Pertaining 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 diversity
Reception of radio waves by two or more antennas
spaced some distance apart.
space wave
A radio wave that travels directly from the transmitter
to the receiver and remains in the troposphere.
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 layer
Irregular cloud-like patches of unusually high
ionization. Often forms at heights near the normal E
layer.
spreader
Insulator used with transmission lines and antennas to
keep the parallel wires separated.
standing wave
The distribution of voltage and current formed by the
incident and reflected waves which have minimum and
maximum points on a resultant wave that appears to
stand still.
standing-wave ratio
The ratio of the maximum (voltage, current) to the
(SWR)
minimum (voltage, current) of a transmission line.
Measures the perfection of the termination of the line.
stratosphere
Located between the troposphere and the ionosphere.
Has little effect on radio waves.
stub
Short section of a transmission line used to match the
also be used to produce desired phase relationships
between connected elements of an antenna.
sudden ionospheric
An irregular ionospheric disturbance that can totally
disturbance (sid)
blank out HF radio communications.
supersonic
Speed greater than the speed of sound.
surface wave
A radio wave that travels along the contours of the
earth, thereby being highly attenuated.
Glossary-13
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