Yagi-Uda Antenna – Basics, Design, and Its Applications

What is the purpose of yagi-uda antenna? These antennas are used for broadcasting commercial or domestic radio communications. They accomplish this task by focusing the antenna’s signal in a specific direction. 

These antennas are versatile and easy to construct. They can be made with simple materials, so they’re very affordable. The most common yagis use a reflector and a balun coil. 

This article will give you an in-depth review of these antennas. We’ll describe the basic principle of the yagi-uda, as well as the key elements that make them work.

What Is Yagi Uda Antenna

The Yagi-Uda Antenna is a directional antenna usually used for transmitting or receiving radio frequency (RF) waves. 

It was invented in 1926 by Shintaro Uda. The antenna is named after Japanese inventor Hidetsugu Yagi. 

They send out their signals in a single, specified direction. The system is made up of a lengthy transmission line and a single driving element that is made up of two rods linked on each end of the line.

Basics of Yagi Uda Antenna

Using standing-wave current components and mutual coupling, Yagi antennas generate a unidirectional traveling-wave pattern. 

It’s comprised of a dipole and several other parasitic components that are close together. The Yagi antenna’s components are often fused to a conducting tube or rod at their centers. 

Being such a directional antenna, Yagi antennas are usually favored for conditions limited to a single polarization. 

Because of their high power handling capability and large directivity, Yagi antennas can be utilized for long-distance transmission. 

The most popular usage requires vertical polarization, which requires adjustment of the dipole’s alignment utilizing adjusting each end’s length on a doublet support grid.

Types of Yagi Uda Antenna

Different types of Yagi Uda antennas are widely used in radio communications. These types are the hemispherical, directional, omnidirectional antenna, etc.

  • Hemispherical Antenna

This type of Yagi Uda is used for transmitting and receiving signals. This is the same type of antenna that a radio station uses to transmit and receive signals. They’re ideal for air-to-ground broadcasting.

  • Directional Antenna
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A directional antenna radiates high power in specific directions. They’re widely used on television stations to broadcast.

  • Isotropic Antenna

Also known as an omnidirectional antenna transmit signal equally in all directions. The antenna is 100% efficient and has a gain of 1 (0 dB) in a sphere centered on it. 

Structure of Yagi Uda Antenna

The antenna consists of three elements arranged in a specific configuration. Directors, reflectors, and driven elements are Yagi-Uda antenna’s components that help transmit and receive radio waves. 

  1. Reflector

A wire, called the reflector, connects the radiating section with an insulator called director elements. The reflector is longer than the directors. 

  1. Directors

It’s shorter and sits on the front of the driven element. When a solid rod is employed as the parasitic element’s feed point rather than a break, the result is an off-tuned, short-circuited dipole. 

They pick up the waves from the driving element and send them back out, albeit with a phase shift based on their lengths.

  1. Driven element 

All other parasitic elements are attached to it. The driven element is the only one that radiates or receives RF energy.

Radiation of Yagi Uda Antenna

A Yagi-Uda antenna is a two-electromagnetic dipole antenna. The radiation of a Yagi Uda Antenna varies with the orientation of the antennas. 

This can be caused by the signal electric field strength change caused by both elevation changes and polarization.

These antennae create an electromagnetic wave field in the direction traveling from the transmission line toward the director. 

The radiation of a Yagi-Uda antenna only depends on the element lengths, so it does not depend on the position of the center conductor. A higher number of directors require greater gain and longer antennas.

Radiation Pattern of Yagi Uda Antenna

Yagi Uda Antenna has an end-fire radiation pattern with a directional transmission. The characters of radiation patterns are two or three-dimensional. 

It includes field strength, polarization or directivity, radiation intensity, and flux density.

The antenna’s beam is parallel to the long axis of the boom. The installation of directors increases antenna gain, while reflectors boost antenna directivity.

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The frequency range of Yagi-Uda antennas is 30 MHz to 3GHz. Being a directional antenna, it needs to be pointed in a specific direction.

Designing of Yagi Uda Antenna

Yagi Uda Antenna
Yagi Uda Antenna

Yagi uda antennae were on every house’s roof for decades. Parasitic components and dipoles constitute a yagi uda antenna. More directors improve antenna directionality, as seen below. 

The antenna features a folded dipole feeder and a longer reflector. Diagram of yagi uda antenna.

Yagi antennas have a boom and a central rod that holds the components. Driven components are connected to transmission lines via black studs. 

A reflector at the driving component’s rear reflects all energy in the emission pattern. The directors before the driving component reflect the wave at the desired angle.

Consider these criteria while designing a Yagi antenna:

PartsLength (λ)
Reflector0.55 – 0.58
Driven component0.45 – 0.5
Director 1 length0.45
Director 2 length0.40
Director 3 length0.35
Dipole-director distance0.125
Reflector-dipole distance0.35

Properties of Yagi Uda Antenna

Here are some of the properties of a Yagi-Uda Antenna.

  • The direction of the driven component is opposite to that of the fed component.
  • Receiver sensitivity is greater for higher frequency band.
  • The antenna has a natural resonant frequency range.
  • Provide good reception in one direction.
  • The balanced Yagi-Uda antenna has the same pattern in both horizontal and vertical planes.
  • These antennas offer very high gain.
  • The frequency band of the driven component is higher than the reflector and lower than the driven component.

Advantages of Yagi Uda Antenna 

Yagi Uda antennas are relatively simple in their design and construction. Here are some of the advantages of Yagi Uda antennas.

  • It’s one of the cheapest types on a per-bandwidth (MHz) basis.
  • The physical size is small compared to other antenna designs.
  • Power handling is generally good.
  • The large reflector area improves their effectiveness in certain environments.
  • Suitable for high-frequency wave.
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Disadvantages of Yagi Uda Antenna

Compare to other antennas, yagi uda antennas have the following disadvantages:

  • The quality of the reception is not very good in noisy areas
  • Depending on the use of the antenna, a thin line can be seen on the screen
  • It’s difficult to change the polarization direction of a yagi uda antenna, and it takes time to do so
  • Length of the antenna increase to obtain high gain
  • Prone to constructive interference 

Applications of Yagi Uda Antenna

The Yagi-Uda antenna has found its way into many different applications. They’re typically used in broadcasting FM, radar, navigation signals, and cellular networks. 

They’re also used in scientific work for their ability to capture and transmit information from multiple sources.


What is the range of a Yagi antenna?

The range of a Yagi antenna depends on the height of the antenna and the frequency of being broadcast. The average range is up to 5 miles but can be increased by adding a reflector.

Can a Yagi antenna be used for TV?

Yes, a Yagi antenna can be used for TV, FM, and other applications.

Why is the Yagi antenna good?

Yagi antenna is good because it’s highly directive and focuses its energy in one direction, which allows you to receive a stronger signal.

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Yagi-Uda antenna is a special antenna used to shoot far away radio waves into the FM radio wave frequencies. The wave travels in one direction, which can be sent through specific locations. 

These antennas can greatly improve the signal-to-noise ratio and thus increase the overall quality of your reception. You can easily set up your Yagi-Uda antenna to run your TV, radio, and other frequencies. So, that is all for now, and we hope you enjoyed reading it.

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