Editing Dummy load (section)

==Radio==
[[File:Waveguide dummy load.jpg|thumb|Microwave dummy load designed to attach to [[waveguide]].]]

{{See also|Antenna (radio)|Standing wave ratio}}
In radio this device is also known as a '''dummy antenna''' or a '''[[radio frequency]] termination'''.  It is a device, usually a [[resistor]], used in place of an [[antenna (radio)|antenna]] to aid in testing a [[radio transmitter]]. It is substituted for the antenna while one adjusts the transmitter, so that no radio waves are radiated so that the transmitter does not [[Electromagnetic interference|interfere]] with other radio transmitters during the adjustments.
(As no dummy load is ideal, however, some radiation does occur).
<ref>{{cite book
|title=ARRL Handbook for the Radio Amateur
|year=1990
|publisher=American Radio Relay League
|location=Newington, Connecticut
|editor=Kleinschmidt, Kirk
|pages=25–21 through 25–23}}</ref>  If a transmitter is tested without a load attached to its output terminals such as an antenna or a dummy load, the power will be reflected back into the transmitter, often overheating and damaging it.   Also, if a transmitter is adjusted without a load, it will operate differently as compared with a load, and the adjustments may be incorrect.

The dummy load ordinarily should be a pure [[Electrical resistance|resistance]]; the amount of resistance should be the same as the [[Electrical impedance|impedance]] of the antenna or transmission line that is used with the transmitter (usually 50 Ω or 75 Ω).<ref>{{cite book
|title=ARRL Handbook for the Radio Amateur
|year=1990
|publisher=American Radio Relay League
|location=Newington, Connecticut
|editor=Kleinschmidt, Kirk
|pages=25–21
}}</ref>
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.<ref>{{cite book
|title=ARRL Handbook for the Radio Amateur
|year=1990
|publisher=American Radio Relay League
|location=Newington, Connecticut
|editor=Kleinschmidt, Kirk
|pages=34–22 through 34–28
}}</ref>  Typically it consists of a [[resistor]] attached to some type of [[heat sink]] to dissipate the power from the transmitter.

The ideal dummy load provides a standing wave ratio ([[Standing wave ratio|SWR]]) of 1:1 at the given [[Electrical impedance|impedance]].

Veterinarian-grade [[mineral oil]], an inexpensive form of mineral oil, is frequently used by [[amateur radio]] operators as coolant in RF dummy loads.