[amsat-bb] Re: Arecibo
domenico.i8cvs at tin.it
Sat Apr 17 09:57:21 PDT 2010
----- Original Message -----
From: "Rick - WA4NVM" <wa4nvm at comcast.net>
To: "i8cvs" <domenico.i8cvs at tin.it>; "Luc Leblanc"
<lucleblanc6 at videotron.ca>; "AMSAT-BB" <amsat-bb at amsat.org>
Sent: Saturday, April 17, 2010 2:54 PM
Subject: Re: [amsat-bb] Re: Arecibo
> You are correct about the antenna. It is a 10 + 10 element crossed yagi.
> At the time I put it back up a few years ago, I didn't know what the FM
> birds were using, RH or LH. So, I took the delay line off and hooked up
> both driven elements to the phasing harness "Y" in what Cushcraft called
> "axial radiation".
> I would think this would give me the "best and worst" of everything. It
> would make my uplink power and downlink receive "half" of what they could
> be if they were phased correctly. Since I don't have any way to switch
> polarity, I use it this way on all the birds. I'm still very surprised I
> heard anything on this setup.
> Rick WA4NVM
Hi Rick, WA4NVM
I know very well the Cushcraft 432-20T and I have one here never used.
It is a very short antenna and it's gain is much lower than the minimum
of 15 dBi required to receive Arecibo.
By the way if you have removed the delay line from the phasing arness
and if you feed both dipoles with the Y arness than you get an "axial
radiation" wich is a linear radiation with a maximum field at 45° and
135° if the antenna elements are crossed like the signe +
Since Arecibo comes to you circularly polarized LHCP you should be
in condition to receive Arecibo not "fair at time" but much better than
actually provided the gain of the 432-20T would be a little bit greater.
Tank you very much for your information.
More information about the AMSAT-BB