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Yagi-Uda antenna History". History of antenna invention and its patents. D. Jefferies, "Yagi-Uda antennas Archived 2005-12-25 at the Wayback Machine". 2004. 'Yagi–Uda emitter used for AESA(active electronically scanned array)' low-frequency radars patents.google.com; Yagi-Uda Antenna. Simple information on basic design, project and measure of ...
A VHF/UHF antenna combines two antennas feeding the same feedline mounted on the same support boom. More extended elements that pick up VHF frequencies are located at the back of the boom and often function as a log-periodic antenna. Shorter elements that receive the UHF stations are located at the front of the boom and often function as a Yagi ...
Polar plots of the horizontal cross sections of a (virtual) Yagi–Uda antenna. The outline connects points with equal field power. The radiation pattern of an antenna is a plot of the relative field strength of the radio waves emitted by the antenna at different angles in the far field. It is typically represented by a three-dimensional graph ...
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.
An antenna may have more than one driven element, although the most common multielement antenna, the Yagi, usually has only one. For example, transmitting antennas for AM radio stations often consist of several mast radiators , each of which functions as a half-wave monopole driven element, to create a particular radiation pattern .
Multiple elements (a fed dipole, a director, and reflectors) were assembled in the 1920s to create narrow transmit and receive antenna patterns. The Yagi-Uda array, better known as the Yagi antenna, is still widely used. [2] Edmond Bruce and Harald T. Friis developed directional antennas for shortwave and microwave frequencies during the 1930s. [2]
Yagi–Uda antenna polar pattern showing pattern of alternating lobes and nulls. In radio electronics, a null is a direction in an antenna's radiation pattern where the antenna radiates almost no radio waves, so the far field signal strength is a local minimum. Nulls occur because different parts of an antenna radiate radio waves of different ...
A quad antenna is a type of directional wire radio antenna used on the HF and VHF bands. A quad is a Yagi–Uda antenna ("Yagi") made from loop elements instead of dipoles: It consists of a driven element and one or more parasitic elements; however in a quad, each of the loop elements may be square, round