Terms

A device that matches the antenna system input impedance to the transmitter, receiver or transceiver output impedance. Also called an antenna-matching network, impedance-matching network or Transmatch.

 A switch used to connect one transmitter, receiver or transceiver to several different antennas.

 A device that picks up or sends out radio frequency energy.

 A method of combining an information signal and an RF (radio-frequency) carrier. In double-sideband voice AM transmission, we use the voice information to vary (modulate) the amplitude of an RF carrier. Shortwave broadcast stations use this type of AM, as do stations in the Standard Broadcast Band (535-1710 kHz). Few amateurs use double-sideband voice AM, but a variation, known as single sideband, is very popular.

The basic unit of electrical current. Current is a measure of the electron flow through a circuit. If we could count electrons, we would find that if there are 6.24 × 1018 electrons moving past a point in one second, we have a current of one ampere. We abbreviate amperes as amps. (Numbers written as a multiple of some power are expressed in exponential notation, as shown here.

A test instrument that measures current.

A station licensed in the amateur service, including necessary equipment, used for amateur communication.

 A radiocommunication service for the purpose of self-training, intercommunication and technical investigations carried out by amateurs, that is, duly authorized persons interested in radio technique solely with a personal aim and without pecuniary interest.

A person holding a written authorization to be the control operator of an amateur station.

Electrical current that flows first in one direction in a wire and then in the other. The applied voltage is also changing polarity. This direction reversal continues at a rate that depends on the frequency of the ac.