________________________________________________________________________Glossary
input impedance
The impedance presented to the transmitter by the
transmission line and its load.
intensity (of sound)
The measurement of the amplitude of sound energy.
Sometimes mistakenly called loudness.
interecept
The point where two lines drawn on a graph cross each
other.
Any disturbance that produces an undesirable response
or degrades a wave.
The 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 storms
Disturbances in the earth's magnetic field that make
communications practical only at lower frequencies.
ionization
The process of upsetting electrical neutrality.
isotropic radiation
The radiation of energy equally in all directions.
leakage current
The small amount of current that flows between the
conductors of a transmission line through the dielectric.
light rays
Straight lines that represent light waves emitting from
a source.
load end
See OUTPUT END.
loading
See LUMPED-IMPEDANCE TUNING.
lobe
An area of a radiation pattern plotted on a polar-
coordinate graph that represents maximum radiation.
long-wire antenna
An antenna that is a wavelength or more long at its
operating frequency.
longitudinal waves
Waves in which the disturbance (back and forth motion)
takes place in the direction of propagation. Sometimes
called compression waves.
loop
The curves of a standing wave or antenna that
represent amplitude of current or voltage.
low frequency (LF)
The range of the radio frequency spectrum extending
from 30 kHz to 300 kHz.
lowest usable
The minimum operating frequency that can be used for
frequency (luf)
communications between two points.
Glossary-7
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