[eagle] Re: A new opportunity (Phase 4 lite?)

Rick Hambly (W2GPS) w2gps at cnssys.com
Sun Jul 22 13:17:26 PDT 2007


After extensive discussions over three days here at the AMSAT-UK meeting I
think we will be OK with a 3.4 GHz downlink but we will need a mitigation
plan in case some country complains. Complaints need to show that we are
generating "harmful interference" which is unlikely especially as our
downlink is wide band data. The Europeans are going to push the issue this
year and possibly get some discussions going in WARC07. We mush get ARRL on
the same page as they will need support from us.

There are at least three mitigation possibilities.

1) Steer the 3.4 GHz antenna away from Region 1. This will be needed in 2
and 3 below, so we will need this capability or we would have to shut down
the 3.4GHz downlink.

2) Use 2.4 GHz as the Region 1 downlink. This would not be hard as we have
another 2.4 GHz transmitter and merging them into one antenna can be done. I
contend that we can live with the pollution on this band if we use a modest
60cm+ dish on the ground pointed up. We should do terrestrial tests with a
transponder on a tower to test this.

3) Use 10GHz as the region 1 downlink. This would require a new antenna
array and we would need to deal with the issues associated with the higher
path loss while keeping things simple for our average users.

After the meeting I had before this trip it is not clear that we will need
to steer the antenna much if at all. My previous information may have been
wrong (or not).

On the 3.4 GHz and 5.6GHz bands we may be able to share existing antennas.
At least that possibility was suggested. I am not so sure that this idea
will stand up to technical scrutiny but it might.

I'm coming home tomorrow so I will be out of touch.


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