HORIZONTALLY POLARIZEDWaves that are radiated with their E field component parallel to the
INCIDENT WAVE(1) The wave that strikes the surface of a medium. (2) The wave that travels from
the sending end to the receiving end of a transmission line.
INDUCTION FIELDThe electromagnetic field produced about an antenna when current and voltage
are present on the same antenna.
INDUCTION LOSSESThe losses that occur when the electromagnetic field around a conductor cuts
through a nearby metallic object and induces a current into that object.
INFRASONIC (SUBSONIC)Sounds below 15 hertz.
INPUT ENDThe end of a two-wire transmission line that is connected to a source.
INPUT IMPEDANCEThe impedance presented to the transmitter by the transmission line and its
INTENSITY (OF SOUND)The measurement of the amplitude of sound energy. Sometimes
mistakenly called loudness.
INTERCEPTThe point where two lines drawn on a graph cross each other.
INTERFERENCEAny disturbance that produces an undesirable response or degrades a wave.
IONOSPHEREThe most important region of the atmosphere extending from 31 miles to 250 miles
above the earth. Contains four cloud-like layers that affect radio waves.
IONOSPHERIC STORMSDisturbances in the earth's magnetic field that make communications
practical only at lower frequencies.
IONIZATIONThe process of upsetting electrical neutrality.
ISOTROPIC RADIATIONThe radiation of energy equally in all directions.
LEAKAGE CURRENTThe small amount of current that flows between the conductors of a
transmission line through the dielectric.
LIGHT RAYSStraight lines that represent light waves emitting from a source.
LOAD ENDSee OUTPUT END.
LOADINGSee LUMPED-IMPEDANCE TUNING.
LOBEAn area of a radiation pattern plotted on a polar-coordinate graph that represents maximum
LONG-WIRE ANTENNAAn antenna that is a wavelength or more long at its operating frequency.
LONGITUDINAL WAVESWaves in which the disturbance (back and forth motion) takes place in
the direction of propagation. Sometimes called compression waves.
LOOPThe curves of a standing wave or antenna that represent amplitude of current or voltage.