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Hi,

A short question that might result in a short answer:

If i use a patch antenna on the receiver side, why would a diversity system still be beneficial? Using 2 patches??? The patch will 99% of the time be better than a dipole anyway!

Thanks,

Tom

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Diversity Rx's are usually used to minimize (and sometimes fully eliminate) multipathing and raleigh fading. The short microwave wavelengths can easily create these issues. Good info on the what/how of multipathing can be found by googling.

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Thanks for the replies!

-AT-Wavess: Considering that our transmitter is always above in the air, I don't think that 1 antenna can be so much better aimed than the other patch antenna

-AT-Mr Cam: So diversity using a (pseudo) omni directional antenna is only usefull to minimize multipathing and raleigh fading. So when you use them in an open field, the advantage is minimal? Conclusion: diversity is only usefull when using directed antennas (a dipole being pseudo-directed since it contains "black spots" in the emission pattern)?

Tom

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Thanks for the replies!

-AT-Wavess: Considering that our transmitter is always above in the air, I don't think that 1 antenna can be so much better aimed than the other patch antenna

Two patch will cover double beam width. You have the posibility of changing to the best signal received by either one. The antenas should be positioned diferent and also have two different configurations of antennas. One for the short distance flights and the other more directive for the long distances.

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I must tell you, I have found no need for diverse antennas.

I have elminated all multipath with the use of 8dB rh circular patch, 20 dB gain receive preamp, 600 mw transmitter, 1/4 wave ground plane transmit antenna.

I have flown over 2200' high and can go further if I dare too. THese of course are my own findings operating in my area.

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Richiela, What patch antenna and preamp are you using? I have just purchased a 2.4 gig. 1 watt TX and receiver. I have been using 900 MHz for a long time. Judging by the videos I have seen 2.4 gig has a crisper picture and antennas are more readily available.

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Judging by the videos I have seen 2.4 gig has a crisper picture

I have to disagree with this particular point. Most people out there are using 2.4GHz systems, so you probably get to see more quality videos from them. However, I don't believe the frequency itself dictates the resolution. What you've probably seen so far is the result of video compression due to the editing software used, or YouTube, GoogleVideo, etc. all of which have horrible compression.

Check out this video from RCDon. He uses a 900MHz system, and I think you will agree the video is VERY high quality...

http://www.rcdon.com/assets/multimedia/Th....ct_768_Kbps.wmv

Edited by twinturbostang

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He's got some great stuff on his website. VERY detailed build threads. And some other great videos. The "Jet Cam Project" video is really cool. And so is the "Flight of the Super Cub". Click on Aircraft Videos to find them.

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