[amsat-bb] Falconsat-3 and APRS HT's? (reflector ant)

[Robert Bruninga]

The June 2004 QST cover photo shows a few of us holding a piece of rabbit
fence bent into a parabola about 2' wide by 1' high with the HT held at the
focal point.  It makes a great gain antenna and is trivial to build.  The
HT's rubber duck is at the focal point so there is no coax.

This is fine for voice satellites, but not so practical for data satelites
which need a laptop and TNC and cables.

https://s3.amazonaws.com/files.qrz.com/h/kb9sxh/cover_shot_QST_bmp.jpg

Bob


-----Original Message-----
From: AMSAT-BB [mailto:amsat-bb-bounces at amsat.org] On Behalf Of Zach
Metzinger
Sent: Tuesday, October 03, 2017 2:16 PM
To: amsat-bb at amsat.org
Subject: Re: [amsat-bb] Falconsat-3 and APRS HT's?

On 10/03/17 07:07, Roy Dean wrote:
> Greg,
>
> You are going to have a very hard time copying Falconsat with
> omni/whip antenna's.   Yes, it's a strong downlink, but "strong" for
> amateur satellites is misleading... It's nowhere near as strong as the
> ISS voice radio, for example, which is easily picked up on my scanner
> duckie.
>
> It's supposed to be over one watt, but I can pick up AO-85 with a
> stronger signal, if that gives you any idea.   Also, Falconsat has
> some really serious polarity fade, so there's another issue.   I can
> go from roughly S7 to 'nuttin by rotating my arrow 10°.

While polarization is still an issue, you might try a square-corner
reflector as a starter antenna:

http://www.qsl.net/ve3rgw/corner.html

Of course, you'll want to upgrade it with a rotator to track the satellite,
but aiming it by hand should work fine. Keep the coax loss low, or, for both
NF improvement and to make up for coax loss, add a LNA right at the antenna.

If you want some historical background on this type of antenna, take a look
at this oldie:

http://www.arrl.org/files/file/History/History%20of%20QST%20Volume%201%20-%20Technology/QS11-40-Kraus.pdf

--- Zach
N0ZGO
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