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Encyclopedia > Passive radiator

A passive radiator or parasitic element is a radio antenna element which does not have any wired input. Instead, it absorbs radio waves radiated from another active antenna element in close proximity, and re-radiates it in phase with the active element so that it adds to the total transmitted signal. This will change the antenna pattern and beam width. A yagi antenna Most simply, an antenna is an electronic component designed to send or receive radio waves. ... A wire is a single, usually cylindrical, elongated strand of drawn metal. ... Information processing In information processing, input is the process of receiving information from an object. ... Radio frequency, or RF, refers to that portion of the electromagnetic spectrum in which electromagnetic waves can be generated by alternating current fed to an antenna. ... Electromagnetic radiation or EM radiation is a combination (cross product) of oscillating electric and magnetic fields perpendicular to each other, moving through space as a wave, effectively transporting energy and momentum. ... Proximity can be freely translated as closeness. ... In telecommunication, the term radiation pattern has the following meanings: 1. ...

Parasitic elements can also be used to alter the radiation parameters of nearby active elements. An example of this is to place a parasitic microstrip patch antenna above another driven patch antenna. This antenna combination resonates at a slightly lower frequency than the original element. However, the main effect is to greatly increase the impedance bandwidth of the antenna. In some cases the bandwidth can be increased by a factor of 10. Xband Patch antenna with dime for size comparison In telecommunication, There are several types of microstrip antennas (also known as a printed antennas) the most common of which is the microstrip patch antenna or patch antenna. ...

comparison of a Yagi with parasidic elements to a log periodic, with all active elements
comparison of a Yagi with parasidic elements to a log periodic, with all active elements

An example of an antenna that uses passive radiators is the Yagi, which typically has a reflector behind the driven element, and one or more directors in front of the driven element, which act respectively like the reflector and lenses in a flashlight to create a "beam". Image File history File links Antenna_yagi_log_comparison. ... A Yagi-Uda antenna. ...

Compare this to a log periodic antenna, which is similar in appearance to a Yagi, but all of its elements are driven directly by the transmitter. Sources Federal Standard 1037C MIL-STD-188 Categories: Telecommunications stubs | Radio frequency antenna types ...

See also



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