Download Citation on ResearchGate | On Nov 30, , Juan Carlos Gómez and others published Diseño de Antenas Yagi Uda Usando. Abstract— This paper presents a simple broad band printed Yagi Uda antenna IndexTerms—Printed YagiUda antenna, Reflectors, Directors, Driven element. Yagi-Udaantenna From Wikipedia, the free encyclopedia Drawing of Yagi-Uda VHF television antenna from , used for analog channels.
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No portion can be reproduced except by permission of the author. The ratio of voltage to current at this point is the driving point impedance Z dp of the 2-element Yagi:.
The antenna was invented in by Shintaro Uda of Tohoku Imperial UniversityJapan with a lesser role played by his colleague Hidetsugu Yagi. The feed antenna is almost always the second from the end, yagi-udz shown in Figure 1.
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The combination yagi-hda the director’s position and shorter length has thus obtained a unidirectional rather than the bidirectional response of the driven half-wave dipole element alone. Curves Re and Im are the resistive and reactive parts of the mutual impedance.
The rest of the elements those to the right of the feed antenna as shown in Figure 1 are known as director elements.
Since the so-called reflector, the longer parasitic element, has a current whose phase lags that of the driven element, one would expect the directivity to be in the direction of the reflector, opposite of the actual directional pattern of the Yagi—Uda antenna.
The first is that the larger the element is, the better of a physical reflector it becomes. In other words, the crest antenaa the forward wave from the reflector element antsnas the driven element just as the crest of the wave is emitted from that element. Yagi Antennas Design Parameters Top: The net effect of these two waves, when added bottom, leftis almost complete cancellation.
Yagi-ura antennas used for amateur radio are sometimes designed to operate on multiple bands. The Yagi-Uda antenna or Yagi Antenna is one of the most brilliant antenna designs.
Yagi published the first English-language reference on the yahi-uda in a survey article on short wave research in Japan and it came to be associated with his name. This appears to have been due to Yagi filing a patent on the idea in Japan without Uda’s name in it, and later transferring the patent to the Marconi Company in the UK. Given the associated costs of erecting an antenna and rotor system above a tower, the combination of antennas for three amateur bands in one unit is a very practical solution.
Thus the directivity of the array indeed is in the direction towards the director. The element to the left of the feed element in Figure 1 is the reflector. That is, they reradiate power which they receive from the driven element they also interact with each other.
Using a second set of traps, a “triband” antenna can be resonant at three different bands. This iterative analysis method is not a straightforward. At the lower frequency, the entire element including the remaining inductance due yagi-uea the trap is close to half-wave resonance, implementing a different Yagi—Uda antenna. The solution of the system then is as follows.
Antenaas of Electrical Engineers of Japan: This page was last edited on 23 Novemberat A full analysis of such a system requires computing the mutual impedances between the dipole elements  which implicitly takes into account the propagation delay xntenas to the finite spacing between elements.
In the next section, we’ll explain the principles of the Yagi-Uda antenna. There are no simple formulas for designing Yagi—Uda antennas due to the complex relationships between yagu-uda parameters such as.
Yagi demonstrated a proof of conceptbut the engineering problems proved to be more onerous than conventional systems. We model element number j as having a feedpoint at the centre with a voltage V j and a current I j flowing into it. However, Yagi always acknowledged Uda’s principal contribution to the design, and the proper name for the antenna is, as above, the Yagi—Uda antenna or array.
These waves combine to produce the net forward wave bottom, right with an amplitude slightly larger than the individual waves. The gain increases with the number of parasitic elements used. Now the difficult computation is in determining that mutual impedance Z 21 which requires a numerical solution.
TV antennas are still a major application of the Yagi antenna. A Yagi—Uda antennacommonly known as a Yagi antennais a directional antenna consisting of multiple parallel elements in a line,  usually half-wave dipoles made of metal rods.
Consequently, these antennas are often empirical designs using an element of trial and erroroften starting with an existing design modified according to one’s hunch.