Dummy Load - Radio

Radio

See also: Antenna (radio) and Standing wave ratio

In radio this device is also known as a dummy antenna or a radio frequency termination. It 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. 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 50 Ω or 75 Ω). 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.

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

Veterinarian-grade mineral oil, an inexpensive source for mineral oil, is frequently used by amateur radio operators as coolant in RF dummy loads.

Read more about this topic:  Dummy Load

Famous quotes containing the word radio:

    “Having a thirteen-year-old in the family is like having a general-admission ticket to the movies, radio and TV. You get to understand that the glittering new arts of our civilization are directed to the teen-agers, and by their suffrage they stand or fall.”
    —Max Lerner (b. 1902)

    “Denouement to denouement, he took a personal pride in the
    certain, certain way he lived his own, private life,
    but nevertheless, they shut off his gas; nevertheless,
    the bank foreclosed; nevertheless, the landlord called;
    nevertheless, the radio broke,

    And twelve o’clock arrived just once too often,”
    —Kenneth Fearing (1902–1961)

    “A bibulation of sports writers, a yammer of radio announcers, a guilt of umpires, an indigence of writers.”
    —Walter Wellesley (Red)