The Yagi antenna or Yagi-Uda antenna or aerial is a particularly popular form of antenna where directivity and gain are required. Although the Yagi has become. The famous yagi-uda antenna is discussed. The background on yagis (the yagi antenna) are given starting with a discussion of the Japanese inventor Yagi. This example optimizes a 6-element Yagi-Uda antenna for both directivity and input match using a global optimization technique.

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However the “Yagi” name has become more familiar with the name of Uda often omitted. John Wiley and Sons. No portion can be reproduced except by permission of the author. A full analysis of such a system requires computing the mutual impedances between the dipole elements [11] which implicitly takes into account the propagation delay due to the finite spacing between elements. This anteena has been translated by MathWorks. Illustration of forward gain of a two element Yagi—Uda array using only a driven element left and a director right.

Our model does not account for the presence of the balun and therefore will match to the typical folded dipole input impedance of. Retrieved 11 September When questioned, the technician said it was an antenna named after a Japanese professor.

The elements are given the uds lengths and spacings so that the radio waves radiated by the driven element and those re-radiated by the parasitic elements all arrive at the front of the antenna in-phase, so they superpose and add, increasing signal strength in the forward direction.

The datsheet lists a input impedance after taking into account a balun. Long for high gain: Very complicated Yagi designs were developed to give adequate gain over the broad television bands. 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. The Yagi is a directional traveling-wave antenna antenw a single driven element, usually a folded dipole or a standard dipole, which is surrounded by several passive dipoles.

For transmitting much better use of the available power is made because it is possible to focus the transmitted power on areas where it is needed. This is close to the gain value reported by the datasheet 8. As alluded to in the previous paragraph, the lengths of the directors are typically less than the resonant length, which encourages wave propagation in the direction of the directors.


This makes the task of finding the right set of parameters satisfying antsna optimization goals particularly challenging and requires the use of global optimization techniques. The feed antenna is almost always the second from the end, as shown in Figure 1. The signal is transmitted by a properly designed The director or directors are made to be shorter than the driven element. Other MathWorks country sites are not optimized for visits from your location.

Yagi Antenna | Yagi-Uda Aerial | Electronics Notes

The Yagi—Uda antenna consists of a number of parallel thin rod elements in a line, usually half-wave long, typically supported on a perpendicular crossbar or “boom” along their centers.

The director or directors are placed in front of the driven element, i.

Geometry of Yagi-Uda antenna. 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. Although the cost is higher than more basic antennas, the Yagi often provides the most cost effective option for gain and directivity. This is machine translation Translated by.

Choose a web site to jda translated content where available and see yzgi events and offers.

The gain and directivity of the Yagi antenna enable improved reception by enabling better levels of signal to noise ratio to be achieved, and by reducing gagi levels by only picking up signals from a given direction. Choose the reflector and director length to be.

This feed antenna is often altered in size to make it resonant in the presence of the parasitic elements typically, 0. Since the Yagi – Uda array is a fairly well-known antenna, it is used as an example to The reflector element is slightly longer than the driven dipole, whereas the directors are a little shorter.

This is the current uuda in the parasitic element due to the current I 1 in the driven element.

One yxgi technique is pattern search, a direct search based optimization technique that has yielded impressive results for antenna design optimization. Yagi antenna, yagi-uda antenna. Although the Yagi has become particularly popular for television reception, it is also used in many other applications, both domestic and commercial or professional.

A Yagi—Uda antennacommonly known as a Yagi antennais a directional antenna consisting of multiple parallel elements in a line, [1] usually half-wave dipoles made of metal rods. Yagi demonstrated a proof of conceptbut the engineering problems proved to be more onerous than conventional systems.


Freq. [MHz]

The optimized Yagi-Uda antenna has a E-plane and H-plane beamwidth that compare favorably to the datasheet listed values of 54 degrees and 63 degrees respectively. In the next section on Yagis, I’ll go further into the design of Yagi-Uda antennas.

There are no simple formulas for designing Yagi—Uda antennas due to the complex relationships between physical parameters such as. The antenna can be optimised to either reduce radiation in the reverse direction by altering the length and spacing of the reflector or it can be optimised to anyena the maximum level of forward gain.

All the other amtena are considered parasitic. This is behind the main driven element, i. Thus the antenna radiates a unidirectional beam of radio waves from the front director end of the antenna. The radio waves from each element are anttena with sntena 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.

One way of thinking about the operation of such an antenna is to consider a parasitic element to be a normal dipole element of finite diameter fed at its centre, with a short circuit across its feed point. It is necessary to choose either maximum front to back ratio or maximum forward gain. By adjusting the distance between the adjacent directors it is possible to reduce the back lobe of the radiation pattern.

However many designs use reflectors consisting of a reflecting plate, or a series of parallel rods simulating a reflecting plate. In fact, that would be the case were we to construct a phased array with rather closely spaced elements all driven by voltages in phase, as we posited.

A picture of Professor Yagi with a Yagi-Uda antenna is shown below. The radiation patterns and input impedance of antennas are sensitive to the parameters that define their shapes.