OPTIMUM WORKING FREQUENCYThe most practical operating frequency that can be used with
the least amount of problems; roughly 85 percent of the maximum usable frequency.
ORIGINThe point on a graph where the vertical and horizontal axes cross each other.
OUTPUT ENDThe end of a transmission line that is opposite the source.
OUTPUT IMPEDANCEThe impedance presented to the load by the transmission line and its source.
PARALLEL RESONANT CIRCUITA circuit that acts as a high impedance at resonance.
PARALLEL-WIREA type of transmission line consisting of two parallel wires.
PARASITIC ARRAYAn array that has one or more parasitic elements.
PARASITIC ELEMENTThe passive element of an antenna array that is connected to neither the
transmission line nor the driven element.
PERIODThe amount of time required for completion of one full cycle.
PITCHA term used to describe the frequency of a sound heard by the human ear.
PLANE OF POLARIZATIONThe plane (vertical or horizontal) with respect to the earth in which the
E field propagates.
POINT OF ZERO DISPLACEMENTSee REFERENCE LINE.
POLAR-COORDINATE GRAPHA graph whose axes consist of a series of circles with a common
center and a rotating radius extending from the center of the concentric circles.
POSITIVE ALTERNATIONThe portion of a sine wave above the reference line.
POWER LOSSThe heat loss in a conductor as current flows through it.
POWER STANDING-WAVE RATIO (PSWR)The ratio of the square of the maximum and
minimum voltages of a transmission line.
PRIMARY COLORS (OF LIGHT)The three primary colors of light (red, green, and blue), from
which all other colors may be derived.
PRISMA triangular-shaped glass that refracts and disperses light waves into component wavelengths.
PROPAGATIONWaves traveling through a medium.
QUALITY (OF SOUND)The factor that distinguishes tones of pitch and loudness.
QUARTER-WAVE ANTENNASame as the Marconi antenna.
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.