[amsat-bb] Re: Portable satellite antenna

Bob Bruninga bruninga at usna.edu
Thu May 5 05:06:48 PDT 2011

> The issue is an antenna.  I live in an antenna 
> restricted area so I am not sure what to do.
> My goal is to work minimally the ISS! :-)
> I own a Kenwood TH-D72A

Walk outside during a pass.  Have the radio configured and working for
normal APRS.  Then just change from 144.39 (APRS) to 145.825 and you should
see everything from the ISS.  No need for anything other than the rubber
duck antenna.

You can confirm the ISS is in APRS mode by checking the age of packets on
this site:
www.ariss.net.  As of right now, it appears the packets are less than an
hour old, so clearly the ISS APRS downlink is on and working.

You can try to send a few packets, but with the rubber-duck you won't make
it in.  With a full sized 19" whip you can make it (but only if you have the
uplink all to yourself).  Of course, the arrow antenna should do it fine.
But there are two other approaches.

1) A simple dipole held horizontal 18" above a ground plane of some kind.
Chicken wire, rabbit fencing, should be about 4' square or so.  This should
give you about 5 dBi gain. Then you should be able to get in during the
center 2 minutes of the overhead pass each day.

2) Use the same ground plane above, and install a 58" vertical whip antenna
on it.  That antenna will give almost 7 dBi gain when the ISS is above 30
degrees (center 2 minutes of an overhead pass).  

When you TX and see the radio flash "MY POSITION", then you know you got in
and everyone else saw you too.  Or send an email to yourself using the APRS
message feature.

Good luck!
Bob, WB4aPR

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