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Hi everybody !

I made this Bi-quad antenna today.

I used this source of information:http://martybugs.net/wireless/biquad/ ,and some minor ideas of my own.

These antennas are supposed to have a radiation pattern somewhat similair to a patch antenna but with higher gain.

Gain is supposed to be 10..12 dBi.

I the next few days, will perform some tests, to compare the properties of this somewhat more complex antenna with the eminent Goof Proof Patch from Mr. RC-Cam, wich is my reference antenna.

If the antenna works good, I will also report back and tell more about how I made it.

Sorry for the poor picture quality, sometimes I manage to make excellent pictures, otherwise not.

Best Regards,

Bosse

post-2-1063217786_thumb.jpg

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cyber-flyer has used one of these antennas with amazing success. Check his site out at www.cyber-flyer.com

Keep in mind they are linear polarized and for the most uniform results, a circular polarized antenna should be mounted on the plane... or an antenna that is both vertically and horizontally polarized like the 'turnstile', which cyber-flyer has also had amazing success with.

Good luck!

Bill

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Yeah, polarization.

That is one the reasons I sometimes get those annoying video-drop outs when making loops rolls or stall-turns, some distance away from the reciever.

The transmitter antenna projecting a near null-lobe towards the reciever, seems not always be the whole story.

Best Regards,

Bosse

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In case you wonder

When looking at the picture, those things you see at the corners of the quads, are supports made of non-conducting material (3 mm bamboo , and hot-glue :ph34r:).

Without those, the antenna would be extremely fragile when based on a thin RG174 transmission cable, wich governs some other dimensions as well.

Best Regards,

Bosse

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I made first test this Saturday. It worked great.

As long as the antenna is approximatly pointed to the airplane, no drop-outs at all occour, at least not within 400 meters and as long as the transmitter antenna does not point directly to the reciever. Gain seems to be high enough to allow for polarization mismatch within this range.

I made a little mistake on the antenna when I crimped the central brass tubing around the coax. That might cause a local disturbance on the impedance as the dielectric gets compressed. I should have soldered it instead. I will fix that and tell some more later.

Best Regards,

Bosse

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Ok,

Feeling like I need to come back to this subject.

I have not had the opportunity to make any flight or other tests recently. I am still conviced Bi-quads are great, only remember they are polarized, horizontally or vertically or at some other weird angle inbetween, you migh find great.

Bi-Quads are the turbo-version of patch antennas in my oppinion, let it be they are somewhat more awkwarad in design, still they are quite simple but with high gain.

Whenever I have some test results, I will come back on this subject.

Best regards,

Bosse

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