Dummy load
From Wikipedia, the free encyclopedia
A dummy load, also known as a dummy antenna or a radio frequency termination, is a device used in place of an antenna to aid in testing a radio transmitter. It is substituted for the antenna while adjusting the transmitter, so that the transmitter does not interfere with other radio transmitters during the adjustments. [1] If a transmitter is tested without a load, such as an antenna or a dummy load, the transmitter could be damaged. Also, if a transmitter is adjusted without a load, it will operate differently than with the load, and the adjustments may be incorrect.
The dummy load ordinarily should be a pure resistance; the amount of resistance should be the same as the impedance of the antenna or transmission line that is used with the transmitter (usually 50Ω or 75Ω).[2] The radio energy that is absorbed by the dummy load is converted to heat. A dummy load must be chosen or designed to tolerate the amount of power that can be delivered by the transmitter. [3]
The ideal dummy load provides a standing wave ratio (SWR) of 1:1 at the given impedance. There are also dummy loads for power supplies, also known as load banks.
[edit] References
- ^ (1990) Kleinschmidt, Kirk: ARRL Handbook for the Radio Amateur. Newington, Connecticut: American Radio Relay League, 25-21 through 25-23.
- ^ (1990) Kleinschmidt, Kirk: ARRL Handbook for the Radio Amateur. Newington, Connecticut: American Radio Relay League, 25-21.
- ^ (1990) Kleinschmidt, Kirk: ARRL Handbook for the Radio Amateur. Newington, Connecticut: American Radio Relay League, 34-22 through 34-28.
[edit] See also
[edit] External links
- Bird Electronics - Power terminations and loads
