What is a Yagi Antenna?
The Yagi Antenna is a directional antenna with narrow bandwidth and a high gain (greater than 10dB). It is named after one of its inventors, Hidetsugu Yagi who developed it with his colleague Shintardo Uda of Tohoku University, Japan in 1926. A Yagi antenna is a directional antenna typically composed of three or more elements spaced on a main boom. One element is the Dipole or driven element. A second element is placed behind the dipole element and is the Reflector element. In front of the dipole element are one or more Director elements.
These director elements concentrate radio signals on the dipole element which absorbs the radio waves enabling signal reception. Normally the more director elements the higher gain of the antenna and the more directive (narrower beamwidth) the antenna is.
The Antenna receives and transmits at different frequencies depending on the length and spacing of the elements. The elements are typically wavelength of the desired frequency of the antenna and are spaced a wavelength apart. For UHF frequencies the Yagi antenna is usually 1 foot wide, and a couple feet long with 10-20 elements.
A Yagi Antenna used on VHF frequencies is much larger and normally has fewer elements As a result of the antenna design, reception is focused in one direction; therefore the Yagi Antenna needs to be pointed in a specific direction to receive a signal. Yagi Antennas are also commonly used for Ham Radio, cellular telephone and WiFi applications.Back to News