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Re: Mode-S Antennas






>From: K5OE@aol.com
>To: cvn65vf94@msn.com
>Subject: Re: [amsat-bb] Mode-S Antennas
>Date: Sat, 10 Feb 2001 13:41:31 EST
>
The 12" would also make a decent
>reflector for a 70 cm helix, but I've pretty much come to the conclusion a
>helix at UHF doesn't make a lot of sense.

Greetings Jerry:

Your conclusions about a helix on UHF sort of mirror mine.  So far here at 
the house I have tried a "standard" helix for 70 which I was pretty happy 
with in terms of performance BUT it was a monster in terms of weight and 
wind loading.  My next stop was the helix without a reflector like the AF9Y 
one (I read the stuff on your web site...cool site) but before the emergency 
which took me "away" I was more investigating the cp quad building one Like 
Howard sent me the pictures of (Thanks Howard...more latter tonight).

My current "Packet" station is two quagis with one on each boom for 2 meters 
and 70cms and they work great.  I ahvent had a helix equal the performance 
of the 70 cm antennas (even my reference one) and its much harder to get the 
feed right.

The advantage of the quad feed (if its simple) would be that I could do 
cross elements on a boom for the same frequency.  I am trying to move the 
antennas so that I have seperate booms/rotars for each band (2 meters, 70 
cms and two dishes one for uplink and one for downlink) to avoid a lot of 
"interference".  Whatever ends up being the 70 cm antenna is going to go 
atop the new tower so it can double as the moonbounce array...

I assumed that you never got the polartity switching to work "real well" on 
the helix?

Robert


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