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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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. A major drawback was the Yagi’s inherently narrow bandwidth. One must take into account an additional phase delay due to the finite distance between the elements which further delays the phase of the currents in both the directors and reflector s. Such a complete exact analysis considering all of the interactions antennas is rather overwhelming, and approximations are inevitable on the path to finding a usable antenna.
The feed antenna is almost always the second from the end, as shown in Figure 1. This appears to have been due to Yagi filing a patent on anfenas idea in Japan without Uda’s name in it, and later transferring the patent to the Marconi Company in the UK. Popular Mechanicspp. This will cause a phase distribution to occur across the elements, simulating the phase progression of a plane wave across the array of elements.
The first is that the larger the element is, the better of a physical reflector it becomes.
This has been computed for two exact half-wave dipole elements at various spacings in the accompanying graph.
Vertically polarized arrays can be seen on the cheeks of the P and on the nose cones of many WWII aircraft, notably the Lichtenstein radar -equipped examples of the German Junkers Ju 88 R-1 fighter-bomberand the British Bristol Beaufighter night-fighter and Short Sunderland flying-boat.
Having the reflector slightly longer than resonant serves two purposes. These elaborate designs create electrical breaks along each element both sides at which point a parallel LC inductor and capacitor circuit is inserted.
The radio waves from each element are emitted with a phase delay, so that the individual waves emitted in the forward direction up are in phase, while the waves in the reverse direction are out of phase. The length of the feed element is given in Figure 1 as F. Radio frequency antenna types Antennas radio Radio electronics Japanese inventions Amateur radio. Views Read Edit View history. This page was last edited on 23 Novemberat The use of traps is not without disadvantages, however, as they reduce the bandwidth of the antenna on the individual bands and reduce the antenna’s electrical efficiency and subject the antenna to additional mechanical considerations wind loading, water and insect ingress.
In the next section on Yagis, I’ll go further into the design of Yagi-Uda antennas. And now knowing the phase and amplitude of I 2 in relation to I 1 as computed above allows us to determine the radiation pattern gain as a function of direction due to the currents flowing in these two elements.
Online Calculator Yagi Uda Antenna
Now the difficult computation is in determining that mutual impedance Z 21 which requires a numerical solution. It is simple to construct and has a high gaintypically greater than 10 dB. The above description is the basic idea of what is going on with the Yagi-Uda antenna.
That is, they reradiate power which they receive from the driven element they also interact with each other. The Yagi antenna consists of a single ‘feed’ or ysgi-uda element, typically a dipole or a folded dipole antenna.
As alluded to in the previous paragraph, the lengths of the directors are typically less than the yagi-dua length, which encourages wave propagation in the direction of the directors. 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.
No portion can be reproduced except by permission of the author. Retrieved 18 September Retrieved 4 July Very complicated Yagi designs were developed to give adequate gain over the broad television bands.
Modern Dictionary of Electronics 7 ed.
Let the driven element be designated 1 so that V 1 and I 1 are the voltage and current supplied by the transmitter.