[amsat-bb] Re: Can someone point me to a simple S-bandhelixconstruction article?

[Michael A. Tondee]

Hello Howard and John,
Thank you both for the links, a quick glance confirms that they already seem 
to have more practical information than what I was finding. I'm just trying 
to do a helix project  to see how well I might receive the AO-51 S-band 
downlink with it. I have several DirectTV dishes here,  and an old barbeque 
grill dish as well but I'm not ready to go that route yet. I'm hoping that 
2.4ghz will still be relatively quiet in my area as I live out in a rural 
community.  You never know though, what neighbors I do have could all have 
wireless LAN's. I hope not.
73,
Michael, W4HIJ
----- Original Message ----- 
From: "Howard Long" <howard at howardlong.com>
To: "'John Franke'" <jmfranke at cox.net>; "'Michael A. Tondee'" 
<mat_62 at netcommander.com>; "'Amsat-Bb at Amsat. Org'" <amsat-bb at amsat.org>
Sent: Tuesday, February 05, 2008 6:17 PM
Subject: RE: [amsat-bb] Re: Can someone point me to a simple 
S-bandhelixconstruction article?


> Hi John
>
>> http://www.wireless.org.au/~jhecker/helix/
>
> An interesting article. I noticed that although the writer discusses that
> the PVC didn't get hot in his microwave oven (inicating it's not lossy), 
> the
> detuning effect of the PVC dielectric isn't discussed. This was one of the
> major problems I had when using PVC pipe as a former. If you can take the
> dielectric effect into account (assuming all PVC pipes have the same
> dielectric properties), then great. Another common fault is to use a
> non-central support.
>
> Had I known the above tips, I would have saved myself weeks of fruitless
> efforts!
>
> Helices are very forgiving antennas in general. The things to pay 
> attention
> to detail on are the former and the matching section if you're interested 
> in
> picking up weak signals.
>
> One further thing - the amount of RF at 2.4GHz now that wasn't there seven
> years ago is astonishing. The pick up from sidelobes of the helix may make
> performance disappointing for satellite use.
>
> I have a number of articles on building helices including:
>
> http://www.g6lvb.com/60cm.htm#PerfectHelix
> http://www.g6lvb.com/quadruple_helix.htm
>
> Cheers, Howard G6LVB
>