What is a Yagi Antenna?
Posted on 3/9/2017 by Nicholas Jones
Have you heard the term ‘Yagi antenna’ and wondered what it is and why it has such a distinctive name? The Yagi is one of the most common types of antenna.
Once you start noticing them, you’ll see them everywhere – on housetops to pull in over-the-air (OTA) TV signals, on programmable LED road signs for reception of message updates, even on remote monitoring stations far from any population center where they transmit collected data back to civilization.
The Yagi is so popular because the design is simple, it’s easy and relatively inexpensive to manufacture and it has high gain (redirected power the antenna receives and transmits). A Yagi antenna typically produces gain of 10 decibels (dB) or more.
A Yagi antenna comprises a conductor and insulated dipoles parallel to the conductor. A photo of a weBoost Yagi antenna is above.
The Yagi antenna is named after Japanese engineer Hidetsugu Yagi. The story varies depending on the source, but Mr. Yagi either (a) co-invented the antenna with engineer Shintaro Uda in the 1920’s, or (b) popularized Uda’s antenna design by publishing the first English language accounts and demonstrating the antenna in the U.S.
So a more accurate name for the design may be the Yagi-Uda antenna, but the universal name is Yagi. Yagi antennas are directional, meaning they must be pointed directly at a signal source for peak performance.
Because they’re directional Yagis are not suitable as mobile antennas, so they’re used at fixed locations. They provide better signal range than do omnidirectional antennas, which receive signals from any direction and transmit in a 360-degree pattern.
Popular uses for Yagi antennas included OTA television, amateur and CB radio and, of course, cell phone reception.
For an excellent explanation of how a Yagi antenna works, I encourage you to watch the video above featuring Don, the Antenna Engineer, from weBoost.
In the video Don uses a Yagi for his directional antenna example, and explains how it works. We’ve started this video at about the 3:00 minute mark where Don begins discussing the Yagi.
If you’re interested in how omnidirectional antennas work, we certainly encourage you to view the video from the beginning.
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