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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 Yagi–Uda antenna. 2008; Yagi-Uda Antennas www.antenna-theory.com
It is difficult to design a single antenna to receive such a wide wavelength range, and there is an octave gap from 216 to 470 MHz between the VHF and UHF frequencies. So traditionally, separate antennas (outdoor antennas with separate sets of elements on a single support boom) have been used to receive the VHF and UHF channels. [6]
For directional antennas, the Yagi antenna is the most widely used as a high gain or "beam" antenna. For television reception, the Yagi is used, as well as the log-periodic antenna due to its wider bandwidth. Helical and turnstile antennas are used for satellite communication since they employ circular polarization.
TV antenna manufacturers often rated their top-of-the-line "deep-fringe" antenna models with phrases like "100 miles VHF/60 miles UHF" if the antenna included UHF reception at all. (In the practice of electrical engineering, the frequency range in which an antenna is to be used is an important factor in its design.)
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. This resulted in much higher gain for UHF, typically on the order of 10 to 14 dB on the Yagi side and 6.5 dB for the log-periodic. [ 5 ]
Drawing of a Yagi–Uda VHF television antenna used for analog channels 2–4, 54–72 MHz (U.S. channels). It has four parasitic elements: three directors (to left) and one reflector (to right) and one driven element which is a folded dipole (double rod) connected to a 300 Ω twin lead feedline down the mast to the television set.
[y] The simple antennas used to make a Yagi-Uda can either all be linear or bent linear antennas, or all loops (a quad antenna) or (rarely) a mixed combination of loops and straight-wire antennas. Yagi–Udas are used for rooftop television antennas, point-to-point communication links, and long distance shortwave communication using skywave ...
The first technique developed was the far-field range, where the antenna under test (AUT) is placed in the far-field of a range antenna. Due to the size required to create a far-field range for large antennas, near-field techniques were developed, which allow the measurement of the field on a distance close to the antenna (typically 3 to 10 ...
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