yagi

A Yagi–Uda antenna or simply Yagi antenna, is a directional antenna consisting of two or more parallel resonant antenna elements in an end-fire array; these elements are most often metal rods acting as half-wave dipoles. Yagi–Uda antennas consist of a single driven element connected to a radio transmitter and/or receiver through a transmission line, and additional "passive radiators" with no electrical connection, usually including one so-called reflector and any number of directors. It was invented in 1926 by Shintaro Uda of Tohoku Imperial University, Japan, with a lesser role played by his colleague Hidetsugu Yagi.Reflector elements (usually only one is used) are slightly longer than the driven dipole and placed behind the driven element, opposite the direction of intended transmission. Directors, on the other hand, are a little shorter and placed in front of the driven element in the intended direction. These parasitic elements are typically off-tuned short-circuited dipole elements, that is, instead of a break at the feedpoint (like the driven element) a solid rod is used. They receive and reradiate the radio waves from the driven element but in a different phase determined by their exact lengths. Their effect is to modify the driven element's radiation pattern. The waves from the multiple elements superpose and interfere to enhance radiation in a single direction, increasing the antenna's gain in that direction.
Also called a beam antenna and parasitic array, the Yagi is very widely used as a directional antenna on the HF, VHF and UHF bands. It has moderate to high gain of up to 20 dBi, depending on the number of elements used, and a front-to-back ratio of up to 20 dB. It radiates linearly polarized radio waves, and can be mounted for either horizontal or vertical polarization. It is relatively lightweight, inexpensive and simple to construct. The bandwidth of a Yagi antenna, the frequency range over which it maintains its gain and feedpoint impedance, is narrow, just a few percent of the center frequency, decreasing for models with higher gain, making it ideal for fixed-frequency applications. The largest and best-known use is as rooftop terrestrial television antennas, but it is also used for point-to-point fixed communication links, in radar antennas, and for long distance shortwave communication by shortwave broadcasting stations and radio amateurs.

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  1. M

    Help Yagi Antenna pasok 938

    Mgs bro nakita ko lng ito, credit sa may ari . Ask ko lng , female sma diba dulo nito , may alam po ba kayo jan na extension na mga 10 meter ang haba , then yung parang sa globe antenna magkadikit ang 2 wire. ? Pati working po ba ito sa 936 at 938 modem ? Feedback need lng mga tol.
  2. K

    Tutorial 3d printed 2.4ghz biquad yagi wifi antenna

    guys share ko lang itong ginawa kong biquad yagi wifi antenna for 2.4 ghz sa YøùTùbé search nyo lang yung turorial at specs pati na rin yung feat ng antenna na ito... yung 3d print ng biquad yagi eh sa thingiverse ko lang dinownload pinaestimate ko lang sa malapit na 3d printing service samen...
  3. M

    yagi antenna installing pa help po tanx

    mga sir bka po may alam kyo about yagi antenna installing s mybro pahelp nmn tanx
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