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A two-element quad antenna used by an amateur radio station A 4-element amateur radio quad antenna. The two men working on it show the scale. The wire loops are almost invisible, suspended on the ends of the crossed supports. A quad antenna is a type of directional wire radio antenna used on the HF and VHF bands.
The experimental Morgenstern German AI VHF-band radar antenna of 1943–44 used a "double-Yagi" structure from its 90° angled pairs of Yagi antennas formed from six discrete dipole elements, making it possible to fit the array within a conical, rubber-covered plywood radome on an aircraft's nose, with the extreme tips of the Morgenstern's ...
The parasitic elements in a Yagi antenna are mounted parallel to the driven element, with all the elements usually in a line perpendicular to the direction of radiation of the antenna. What effect a parasitic element has on the radiation pattern depends both on its separation from the next element, and on its length.
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.
[ab] 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 ...
In antenna terms, each of the conductors making up the antenna is known as an element. [9] To calculate the net result, NEC breaks the antenna's elements into a number of sampled points, called segments. It uses simple calculations based on the diameter of the conductor and the wavelength of the signal to determine the induced voltage and ...
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] Up to eight batwing antennas are usually stacked vertically and fed in phase to make a high gain omnidirectional antenna for TV ...
A Yagi antenna uses multiple dipole elements, which include "reflector" and "director" dipole elements. The "reflector" is the longest dipole element and blocks nearly all the signal coming from behind it, hence a Yagi has no front vs. back directional ambiguity: The maximum signal only occurs when the narrowest end of the Yagi is aimed in the ...