General: Quad Antennas

Approximately how long is each side of the reflector element of a quad antenna?

A. Slightly less than 1/4 wavelength
B. Slightly more than 1/4 wavelength
C. Slightly less than 1/2 wavelength
D. Slightly more than 1/2 wavelength

So lets look at what a “quad antenna” entails.  As you might have guessed from the name, the antenna design has four sections to each element.  Most often its arranged in a pair of squares.  See the multi-band quad in the image.  Each pair of squares is for a different band or frequency range.  It’s a directional antenna, also, with the signal aimed “through” the pair of square sections.  The design is basically a hybrid of a “loop” and a “yagi.”

Without going into too much detail.  Lets say that we want our antenna to resonate more or less a full wavelength.  But, enter the QUAD.  So if we take that full wavelength, which is often very long, and divide by four, we get 1/4 wavelength.

However, you need that piece to resonate the desired 1/4 wavelength.  If its too short, you won’t get there.  If its just a bit too long, though, you’ll be able to get it really close.  After all, what antenna isn’t a compromise?

Therefore the answer is B. Slightly more than 1/4 wavelength


Image: https://commons.wikimedia.org/wiki/File:%D0%90%D0%BD%D1%82%D0%B5%D0%BD%D0%BD%D0%B0_(20.01.2011)_-_panoramio_-_%D0%95%D0%B2%D0%B3%D0%B5%D0%BD%D0%B8%D0%B9_%D0%9A%D0%B0%D1%82%D1%8B%D1%88%D0%B5%D0%B2.jpg

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