Codan Radio Radio Repeater Systems Training Guide - Manual (Page 81)

RADIO REPEATER SYSTEM | TRAINING GUIDE
Appendix J: Glossary of Terms Page 73
APPENDIX J: GLOSSARY OF TERMS
Antenna
An elevated device for radiating and
receiving radio waves. It changes
electrical currents into electromagnetic
radio waves and vice versa.
Antenna Gain
The increase in power radiated by
and / or received by an antenna in a
given direction compared to the power
radiated in the same direction by a
standard omni-directional antenna.
Antenna Polarization
The orientation of the radiated electric
fi eld in relation to the surface of the
earth.
Antenna Array
An arrangement of two or more
antennas spaced and connected so that
they are in phase and their effects are
additive.
Attenuation
The reduction in energy which
accompanies the passage of an
electronic wave through telephone lines,
equipment or space.
Automatic Frequency Control (AFC)
A circuit that allows a receiver to “lock
on” to a transmitter’s signal, and follow
any deviations that may occur in the
transmitter’s frequency.
Auxiliary Power Unit (APU)
A machine or device that supplies
power, usually electrical, when the main
or usual source fails or is interrupted. A
standby power source.
Band, Frequency
Frequencies which are within two
defi ned limits, and are used for the
specifi ed purpose.
Bandwidth
The amount or portion of the frequency
spectrum required to transmit the
desired information.
Base Station
A transmitter / receiver unit located in a
fi xed location. Term is often shortened to
“base”.
Beam
A confi guration of radiated energy
whose rays are sharply directional and
parallel.
Beam Antenna
An antenna array that concentrates
radio transmission into a narrow
directional path or receives radio signals
only from a narrow sector of the total
horizon.