Yagi-uda

December 21, 2023 Post a Comment

Yagi-uda

The waves from the multiple elements superpose and interfere to enhance radiation in a single direction, increasing the antenna's gain in that direction. Also called a beam antenna and parasitic array, the Yagi is very widely used as a directional antenna on the HF, VHF and UHF bands.

What is a Yagi antenna used for?

A Yagi antenna is used for communications in a medium range of three to five miles between two points. It can also be used as a bridge antenna to connect clients to an access point. This term is also known as a Yagi-Uda array or patch antenna.

What does Yagi stand for?

Definition of Yagi : a highly directional and selective shortwave antenna consisting of a horizontal conductor of one or two dipoles connected with the receiver or transmitter and of a set of nearly equal insulated dipoles parallel to and on a level with the horizontal conductor.

How does a Yagi-Uda antenna work?

The Yagi antenna propagates electromagnetic field energy in the direction running from the driven element toward the director(s), and is most sensitive to incoming electromagnetic field energy in this same direction. The more directors a Yagi has, the greater the forward gain and the longer the antenna becomes.

How directional is a Yagi?

Yagi Antennas A yagi antenna is the most common type of directional cellular antenna. They are slightly more advanced than omni antennas, and once installed high on a building or wall will pull in signal in a 45 to 90 degree field in the direction they point.

What is the frequency range of Yagi-Uda antenna?

The frequency of Yagi-Uda antenna ranges between 3 MHz to 300 GHz. Frequencies ranging between 3 MHz and 300 GHz are categorized into VHF, LF, UHF, HF, SHF and EHF [1-6].

Why is Yagi antenna good?

Advantages of Yagi Antennas Most of these antennas have a 50° to 70° beam width. Because they focus all their input in one direction, they put out high gain relative to omnidirectional antennas. This makes them ideal for receiving lower strength signals. Their high gain gives these antennas relatively good range.

What are the three elements of Yagi-Uda antenna?

In the Yagi-Uda antenna, there are mainly three element-Reflector, Directors, Driven element.

Can a Yagi antenna transmit a signal?

Since yagi antennas are designed to only send and receive from a single direction, they are able to transmit a much stronger signal than omnidirectional antennas and can also receive weaker signals making them ideal for situations where the existing cell phone signal strength is low.

What is the radiation pattern of Yagi-Uda antenna?

Explanation: Radiation pattern of a Yagi-Uda antenna is end-fire. It has its main beam parallel to the axis of antenna (boom). The addition of directors will increase the gain of antenna while reflectors will increase the directivity of antenna.

What are the three types of antennas?

The three main types of antenna are directional, semi-directional, and omni-directional.

What are the parts of a Yagi antenna?

Here's a diagram:

Boom. This is the part of the antenna to which all the other elements are fastened.
Directors. These are the parasitic elements of the antenna. ...
Driven Element ("Dipole") This is what radiates or receives the radio waves for the antenna. ...
Reflector.

What is the gain of a Yagi antenna?

The practical gain of a Yagi is 6 to 20 dBi, depending on the number of elements. As a consequence of its ability to provide antenna gain in a specific direction, the Yagi antenna has a narrow frequency range. Typically the bandwidth is about 10% from the operating frequency.

How does a Yagi antenna focus RF energy?

A Yagi antenna uses several elements to form a directional array. A single driven element, typically a dipole, propagates RF energy; elements placed immediately in front of and behind the driven element re-radiate RF energy in phase and out of phase, enhancing and retarding the signal, respectively.

Should a Yagi be vertical or horizontal?

A Yagi antenna should also be pointed so that the largest fins are closest to the mast and the shortest fins pointed at each other. For Omni directional antennas, they should be in most cases pointed directly vertical. That is to say, pointed directly up into the sky.

Does Yagi antenna need line of sight?

If there is no line of sight, a Yagi antenna will not perform well. Increasing the gain of an omni antenna results in less energy sent vertically and more energy sent horizontally, extending the range.

Does a Yagi antenna need to be grounded?

The Yagi does not need to be grounded. However, we recommend a lightning surge protector in all building installations. The surge protector will prevent an electrical surge from damaging your amplifier.

How is Yagi Uda calculated?

Designing a Yagi Uda Antenna Reflector length =150/f(MHz) =150/106=1.41 Meters. Driven element length =143/f(MHz) =143/106=1.35 Meters. First Director length =138/f(MHz) =138/106=1.30 Meters. Second Director length=134/f(MHz) =134/106=1.26 Meters.

What is the impedance of a Yagi antenna?

In most antenna designs, the feedline impedance will be 50 ohms, but usually the feed point impedance of the Yagi is rarely 50 ohms. In most cases it can vary from approximately 40 ohms to around 10 ohms, depending upon the number of elements, their spacing and the antenna's pattern bandwidth.

How do I increase Yagi antenna gain?

The gain of a Yagi can be increased by increasing the number of elements but every additional element has got a less and less effect. For moderate numbers of elements, the forward gain is proportional to the number of elements. The array of elements of the Yagi antenna can be described as a slow wave structure.