PHASE SHIFTERA device used to change the
phase relationship between two ac signals.
PLANE OF POLARIZATIONThe plane (vertical
or horizontal) with respect to the earth in which
the E-field propagates.
POSITIVE ALTERNATIONThe portion of a
sine wave above the reference line.
POWER GAINThe ratio of the radiated power
of an antenna compared to the output power of
a standard antenna.
A measure of antenna
efficiency usually expressed in decibels. Also
referred to as POWER RATIO.
POWER LOSSThe heat loss in
current flows through it.
a conductor as
POWER RATIOSee POWER GAIN.
P O W E R S T A N D I N G W A V E R A T I O
(PSWR)The ratio of the square of the maxi-
mum and minimum voltages of a transmission
PROPAGATIONWaves traveling through a
PROBEA metal rod that projects into, but is
insulated from, a waveguide or resonant cavity
and used to inject or extract energy.
QUARTER-WAVE ANTENNASee MARCONI
RADIATION FIELDThe electromagnetic field that
detaches itself from an antenna and travels
RADIATION LOSSESThe losses that occur when
magnetic lines of force about a conductor are
projected into space as radiation and are not
returned to the conductor as the cycle alternates.
RADIATION PATTERNA plot of the radiated
energy from an antenna.
RADIATION RESISTANCEThe resistance, which
if inserted in place of an antenna, would consume
the same amount of power as that radiated by
RADIO FREQUENCIESElectromagnetic frequen-
cies that fall between 3 kilohertz and 300
gigahertz and are used for radio communications.
RADIO HORIZONThe boundary beyond the
natural horizon in which radio waves cannot be
propagated over the earths surface.
RADIO WAVE(1) A form of radiant energy that
can neither be seen nor felt; (2) An electromag-
netic wave generated by a transmitter.
RAREFIED WAVEA longitudinal wave that has
been expanded or rarefied (made less dense) as
it moves away from the source.
RECEIVERThe object that responds to a wave or
disturbance. Same as detector.
RECEIVING ANTENNAThe device used to pick
up an rf signal from space.
RECEIVING ENDSee OUTPUT END.
RECIPROCITYThe ability of an antenna to both
transmit and receive electromagnetic energy with
REFLECTED WAVE(1) The wave that reflects
back from a medium; (2) Waves traveling from
the load back to the generator on a transmission
line; (3) The wave moving back to the sending
end of a transmission line after reflection has
REFLECTION WAVESWaves that are neither
transmitted nor absorbed, but are reflected from
the surface of the medium they encounter.