[amsat-bb] Re: NASA's American Student Moon Orbiter...
aa2tx at comcast.net
Wed Jul 2 19:42:26 PDT 2008
At 08:28 PM 7/2/2008, Andrew Glasbrenner wrote:
>The moon is roughly 360,000 to 400,000 km away. By comparison, AO-40 had a
>apogee of about 60,000km. At 2.4Ghz, that's about 16db difference each way.
>Put AO-40 at the moon, and if I'm doing this right, you'd need about 32
>times the ground station antenna both coming and going to get with a few db.
>I'm gonna need a bigger rotor for sure! I'm sure smarter folks will check my
Let me add a little about antenna size. You are correct, the path loss is
around 16 dB higher each way. This is about 40 times higher path loss.
Antenna gain is proportional to area (ignoring efficiency)
so to get 40 times the gain you would need a little more than
6 times the diameter for a dish antenna. So, if you could receive AO-40
on 2.4GHz with a 1 meter dish, you would need something around
a 6 meter diameter dish to receive AO-40 if it were on the moon.
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