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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; [1] these elements are most often metal rods (or discs) acting as half-wave dipoles. [2]
Radiation resistance is affected by antenna height above ground, element spacing, and environmental conditions. However, values will be higher than for a Yagi and more closely matched to a 50 Ohm coaxial feed. Lower boom height "A two-element, three-band quad, with elements mounted only 35 feet above ground, will give good performance in ...
Adding a director to this, to give a 3 element Yagi, gives a gain of about 7 dB over a dipole. As a rule of thumb, each additional parasitic element beyond this adds about 1 dB of gain. [2] In an example of a parasitic element that is not rod-shaped, a parasitic microstrip patch antenna is sometimes mounted above another driven patch antenna ...
Each element is longer than the last, and to maintain accuracy, the later elements are divided into more segments. All measurements in NEC use metres, so the first element is 2 metres wide, running from -1 to 1. The GE line indicates the end of the geometry section. At this point, NEC scans the geometry for overlapping endpoints, which it then ...
They typically have gains between 10 and 20 dBi depending on the number of director elements used, but their bandwidths are very narrow. [ab] Moxon antenna Also called a Moxon rectangle; it is a rectangular-shaped, folded version of a two-element Yagi-Uda, hence a minimal parasitic array. [14] Quad
Early TV broadcast antennas used "cigar shaped" elements, shown in image of 1939 RCA Empire State Building antenna above. A common shape today is the batwing or superturnstile antenna, used for television broadcasting in the VHF or UHF bands [ 8 ] The batwing shape of each element produces an antenna with wide impedance bandwidth. [ 1 ]
A rooftop television antenna, an endfire parasitic array consisting of a combination of a Yagi and log periodic antenna Parasitic array – This is an endfire array which consist of multiple antenna elements in a line of which only one, the driven element, is connected to the transmitter or receiver, while the other elements, called parasitic ...
However, a Yagi with the same number of elements as a log-periodic would have far higher gain, as all of those elements are improving the gain of a single driven element. In its use as a television antenna, it was common to combine a log-periodic design for VHF with a Yagi for UHF, with both halves being roughly equal in size.