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Playboysenior

Antenna queries

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Hi Guys

I’ve realised that there are big gaps in my knowledge on aerials – so please excuse the dumbness of these questions...

I’m on 2.4GHz and have a 10mw transmitter on the camera on the airplane, with the aerial mounted vertical.

I’ve been using the little ‘twig’ omni directional aerial that comes with the Chinese rx. I also have an 8db patch antenna. I’ve tended to use the patch for when I know I’ll mainly be flying in a certain direction and the twig for buzzing around the field. But I do get plenty of outages and at one field I seem to always get the effect that I am looking through a gauze filter.

I had understood that the patch antenna had to be mounted vertically to keep ‘in polarity’ with the aircraft antenna – but I notice in photos and vids that many folks have them mounted at a 45 degree angle. Which is correct?

If it works ok having a patch antenna at 45 degrees, then is it also ok to have an omni directional aerial at 45 degrees. I don’t suppose that it’s going to pick up much from the ground behind it, but on the other side it is covering the entire sky....? I’m guessing that there is a deep flaw in that thinking?

Also, looking on the Hyperlink site, I’ve found some omni directional aerials that don’t have the big dead spot vertically above them. Would they be winners? What about if tilted back at 30 degrees?

http://www.hyperlinktech.com/web/pdf/hg2407mgu.pdf

(The pictures are on the hyperlink page at the bottom)

http://www.hyperlinktech.com/web/re05u.php

I tend to prefer to fly my fpv around my base field, rather than out into the middle distance, hence my desire to find an aerial that is going to work well with the plane overhead and behind as well as in front. Maybe I need to change my flying style? Would a patch aerial flat on its back work?

I have just ordered an Oracle diversity receiver unit. I had thought to have a patch aerial on one rx and an omni on the other. Is there an optimal set up? Two patch aerials pointing 40 degrees apart, one 25 degrees back from vertical, the other 40 degrees back from vertical?

Any thought or tips would be most appreciated.

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Hi Guys

I’ve realised that there are big gaps in my knowledge on aerials – so please excuse the dumbness of these questions...

I’m on 2.4GHz and have a 10mw transmitter on the camera on the airplane, with the aerial mounted vertical.

I’ve been using the little ‘twig’ omni directional aerial that comes with the Chinese rx. I also have an 8db patch antenna. I’ve tended to use the patch for when I know I’ll mainly be flying in a certain direction and the twig for buzzing around the field. But I do get plenty of outages and at one field I seem to always get the effect that I am looking through a gauze filter.

I had understood that the patch antenna had to be mounted vertically to keep ‘in polarity’ with the aircraft antenna – but I notice in photos and vids that many folks have them mounted at a 45 degree angle. Which is correct?

If it works ok having a patch antenna at 45 degrees, then is it also ok to have an omni directional aerial at 45 degrees. I don’t suppose that it’s going to pick up much from the ground behind it, but on the other side it is covering the entire sky....? I’m guessing that there is a deep flaw in that thinking?

Also, looking on the Hyperlink site, I’ve found some omni directional aerials that don’t have the big dead spot vertically above them. Would they be winners? What about if tilted back at 30 degrees?

http://www.hyperlinktech.com/web/pdf/hg2407mgu.pdf

(The pictures are on the hyperlink page at the bottom)

http://www.hyperlinktech.com/web/re05u.php

I tend to prefer to fly my fpv around my base field, rather than out into the middle distance, hence my desire to find an aerial that is going to work well with the plane overhead and behind as well as in front. Maybe I need to change my flying style? Would a patch aerial flat on its back work?

I have just ordered an Oracle diversity receiver unit. I had thought to have a patch aerial on one rx and an omni on the other. Is there an optimal set up? Two patch aerials pointing 40 degrees apart, one 25 degrees back from vertical, the other 40 degrees back from vertical?

Any thought or tips would be most appreciated.

about the angle of mounting the aerial, why don't you try it youself? I'm also curious to know your testing result. So far as I know, the video signal gets a bit distorted when my plane is flying on the left most of the 8dbi patch antenna, err, it is like 90 degrees left at the patch antenna.

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I had understood that the patch antenna had to be mounted vertically to keep ‘in polarity’ with the aircraft antenna – but I notice in photos and vids that many folks have them mounted at a 45 degree angle. Which is correct?

Do you mean 45 deg rotation or leaning back ? leaning back is ok.

Also, looking on the Hyperlink site, I’ve found some omni directional aerials that don’t have the big dead spot vertically above them. Would they be winners? What about if tilted back at 30 degrees?

I have not seen any that don't have a weak spot above them but if you have one why would you want to tilt it back ?

Would a patch aerial flat on its back work?

yes if it is circular polarized.

I have just ordered an Oracle diversity receiver unit. I had thought to have a patch aerial on one rx and an omni on the other. Is there an optimal set up? Two patch aerials pointing 40 degrees apart, one 25 degrees back from vertical, the other 40 degrees back from vertical?

No you can use it any way you want depending on the aerials you want to use and the way you want to fly.

A patch pointing to your flying zone and an omni are popular.

Terry

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Hi Guys

Thanks for the info.

I did some trials the other day - ground to ground.

With a standard omni directional aerial I was surprised to find that I had a good picture at 400 metres.

With an 8dbi patch antenna the picture was slightly better. Aiming the antenna at 45 degrees to one side hardly made any difference. At 90 degrees the picture was poor - but I could still have orientated a model. 180 degrees was unusable. At all angles, putting the patch on its side seriously reduced the picture quality (polarisation is important).

I then moved to 150 metres. At this distance I had a 'usable' picture even with the patch antenna at 180 degrees.

Overall I was happily surprised by these results.

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