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Old Oct 25, 2010, 05:16 PM
IBCrazy is offline
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Amherst, VA
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Mini-HowTo
DIY BiQuad 11dbi antenna tutorial!

For those who are looking to transition into long rang flights, this just might be the antenna for you. The BiQuad is a fairly simple to build 11dbi antenna that puts 99% of it's beam right where you need it - out front. No loss of flight area due to sides lobes, compact design and many mounting capabilites make this an excellent upgrade to your patch or 9dbi Yagi. The antenna gives a nice 50-55 degree beam width for you to fly in on your long distance ventures.

So, first a little explanation, then on to building it.


What exactly is a BiQuad antenna? - A BiQuad is two full wave bisquare antennas in parallel in front of a reflector 1/8 wavelength away. Without the reflector, the propagation pattern is very much like that of a dipole. The reflector drives the beam outward.

What is the gain/beam width? ~ 11dbi with a 50 degree beam

Why should I fly it? There are several advantages to the BiQuad. First and foremost, unlike the patch, this antenna is NOT ground plane dependent. While being close to the ground will actually increase the gain some, it is not necessary. It also has small side lobes in the far field, and thus you can fly in close without flying into a null. There is, however, still a null directly overhead just like a dipole would have.

How difficult is it to build? – This antenna is fairly good when it comes to tolerances, so precision isn’t a large contributor like many other high gain antennas. However getting the “bow tie” straight is a bit tedious. Also, unbraiding and soldering the coaxial shield is tedious, but not difficult. If you are somewhat handy, this antenna shouldn’t be a problem.

Below are the radiation patterns and pictures of the BiQuad antenna.

Ready to build? Read on

-Alex
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