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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 ...
It is a two element Yagi-Uda antenna with folded dipole elements, and no director(s). Because of the folded ends, the element lengths are approximately 70% of the equivalent dipole length. The two-element design gives modest directivity (about 2.0 dB ) with a null towards the rear of the antenna, yielding a high front-to-back ratio : Gain up to ...
German physicist Heinrich Hertz first demonstrated the existence of radio waves in 1887 using what we now know as a dipole antenna (with capacitative end-loading). On the other hand, Guglielmo Marconi empirically found that he could just ground the transmitter (or one side of a transmission line, if used) dispensing with one half of the antenna, thus realizing the vertical or monopole antenna.
The addition of parasitic elements gives a diminishing improvement in the antenna's gain. [2] Adding a reflector to a dipole, to make a 2 element Yagi, increases the gain by about 5 dB over the dipole. Adding a director to this, to give a 3 element Yagi, gives a gain of about 7 dB over a dipole.
Yagi–Uda coplanar parasitic dipole array, with a folded dipole driven element, made for analog TV channels 2–4 and 47–68 MHz Log periodic coplanar dipole array for 140–470 MHz Sector antennas (white bars) on cell phone tower .
Since these have only one driven element they are often called "antennas" instead of "arrays". Yagi–Uda antenna or Yagi antenna – this endfire array consists of multiple half-wave dipole elements in a line. It consists of a single driven element with multiple "director" parasitic elements in the direction of radiation, and usually a single ...
The Yagi and the LPDA designs look very similar at first glance, as they both consist of a number of dipole elements mounted along a support boom. The Yagi, however, has only a single driven element connected to the transmission line, usually the second one from the back of the array, the remaining elements are parasitic .
The top shows the directive pattern of a horn antenna, the bottom shows the omnidirectional pattern of a simple vertical dipole antenna. In the field of antenna design the term radiation pattern (or antenna pattern or far-field pattern ) refers to the directional (angular) dependence of the strength of the radio waves from the antenna or other ...