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Re: AMSAT has a SECRET: why not 10m instead of V band



A 10-meter downlink doesn't work very well on a satellite that has an apogee
of 35,000 km. Path loss is 153 dB and the noise level at the quietest
location on earth during the quietest season of the year is 18 dB above
thermal noise. 100 watts EIRP per user is required at the satellite to give
a 17 dB SNR with a dipole antenna.

The advantage of higher frequencies is that, compared to 10 meters, 2 meters
is 15 dB quieter, 70 cm is 24 dB quieter, and 13 cm is 38 dB quieter. The
most costly item other than the fuel for the rocket engine is the power to
run the transmitter.

73,

John
KD6OZH

----- Original Message -----
From: <sco@sco-inc.com>
To: <amsat-bb@AMSAT.Org>
Sent: Friday, 01 June 2001 15:41 UTC
Subject: [amsat-bb] AMSAT has a SECRET: why not 10m instead of V band
> I might do away with a 2m link in favor of a 10m downlink capability. That
> way any ham or SWL who has a general coverage receiver 160-10m will be
able
> to hear the satellite. Once they hear it they might get interested and
want
> to talk thru it too. I would suggest that more people  (hams and SWLs)
have
> a general coverage HF receiver as compared to an all mode VHF receiver.
> They are less expensive to buy too.
>
> A 10m downlink could be heard well on a dipole antenna.
>
> Make a satellite in an AO-40 orbit (that was planned).
> With 10m and S band downlinks.
> With U and L band uplinks.
>
> W4SCO


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