What is a Yagi antenna?
Posted on 9/23/2015 by Nicholas Jones
You have probably heard the term ‘Yagi antenna’ and perhaps wondered what it is and why it has such a distinctive name. The Yagi, shown above, is one of the most common antenna types.
Once you start noticing them, you’ll see them everywhere – on housetops to pull in over-the-air television signals, on progammable 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 relativley inexpensive to manufacture and it has high gain (or increase in the 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. An illustration of a Yagi antenna is above.
The Yagi antenna is named after Japanese engineer Hidetsugu Yagi. Sources vary, 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.
Rather than try to explain how a Yagi antenna works, I encourage you to watch the video above featuring Don, the Antenna Engineer, from weBoost. In the video Don explains the difference between directional and omnidirection antennas. He uses a Yagi antenna as his directional example, and explains how it works.
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