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3 Element Yagi Antenna Calculator

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This page covers a 3-element Yagi Antenna calculator, explaining the formulas and basics behind it. Calculators for other antenna types, such as parabolic, horn, dipole, and patch antennas, are also mentioned.

What is a Yagi Antenna?

The simple Yagi Antenna is shown in Figure 1. It consists of three elements: the director, the dipole, and the reflector. It may have one or multiple directors.

Dipole (Driven Element): This is the feed point where the feedline is typically attached from the transmitter. It facilitates the transfer of energy from the transmitter module to the antenna. The feed point is located at the center of the driven element. It becomes resonant when its electrical length is about half of the wavelength of the operating frequency.
Director: Designed primarily for receiving EM waves, it’s the shortest of the parasitic elements. Its length is approximately 5% shorter compared to the driven element and has a higher resonant frequency. The director helps achieve the desired gain and directional pattern. The spacing between directors usually ranges from 0.1λ to 0.5λ or more. The gain of a Yagi antenna depends on the length of the antenna array and not on the number of directors used.
Reflector: Placed at the rear of the dipole or driven element. Its length is usually 5% longer compared to the driven element. The spacing of the reflector from the driven element is about 0.1λ to 0.25λ. The spacing also depends on bandwidth, gain, front-to-back ratio, and sidelobe pattern specifications.

3-element Yagi Antenna