Transponder aerial
- juliant
- Seasoned Member
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- Joined: Thu May 22, 2008 2:26 am
- Location: Koromatua, New Zealand
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Transponder aerial
Hi
What is the best place to mount the transponder aerial? and what sort of ground plane is required . Anyone got any pics?
thanks
Julian
NZ
What is the best place to mount the transponder aerial? and what sort of ground plane is required . Anyone got any pics?
thanks
Julian
NZ
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- Veteran Member
- Posts: 181
- Joined: Sat Jan 27, 2007 11:01 pm
- Location: Hampton, NH 7B3
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- Veteran Member
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- Location: Orwigsburg, PA
Antenna's
Do a search on "antenna mounting" and you will find some good info from Wes. Here is the link, if it works.
Paul, PA
http://www.wingsforum.com/viewtopic.php ... ht=antenna
Paul, PA
http://www.wingsforum.com/viewtopic.php ... ht=antenna
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- Veteran Member
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- Joined: Sat Jan 27, 2007 11:01 pm
- Location: Hampton, NH 7B3
- juliant
- Seasoned Member
- Posts: 72
- Joined: Thu May 22, 2008 2:26 am
- Location: Koromatua, New Zealand
- Contact:
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- Veteran Member
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- Location: toccoa Ga
Julian I've been trying to post a reply to you for threee days and my piece of crap computer hasn't let me. Anyway here at the factory we put the transponder ant. on the plate that covers the opening at the rear on the bottom of the fuse. That way no additional metal has to be put into the bottom of the plane. Jak
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- Wes
- Premium Member
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- Joined: Mon Jan 23, 2006 10:32 pm
- Location: Satellite Bch, Florida
Transponder Antenna Mount
Wooohhh, wait a minute guys, are we talking about transponder antennas?
Transponders operate around 1 GHZ and the signal attenuation in coax at this freq is terrible. Some coaxes are better than others, but readily available coax types that are over 6 ft in length will attenuate the TX and Rcv signals well in excess of manufacturer reccomended specs. (1.5 db max. for the Garmin 327).
So again, in my opinion you are severely compromising your ATC transponder system if you run long, lossy coax to the tail mounted antenna. Will it 'work' ?, well maybe, - will it work on the edge of the radar coverage area, where you really might like to have it ? - probably not!
In this case, longer is definitely not better!
'Just' my opinion.
Wes
Transponders operate around 1 GHZ and the signal attenuation in coax at this freq is terrible. Some coaxes are better than others, but readily available coax types that are over 6 ft in length will attenuate the TX and Rcv signals well in excess of manufacturer reccomended specs. (1.5 db max. for the Garmin 327).
So again, in my opinion you are severely compromising your ATC transponder system if you run long, lossy coax to the tail mounted antenna. Will it 'work' ?, well maybe, - will it work on the edge of the radar coverage area, where you really might like to have it ? - probably not!
In this case, longer is definitely not better!
'Just' my opinion.
Wes
Kit # 95
Low and Slow - The only way to go!
Low and Slow - The only way to go!