[amsat-bb] Re: The Moon is our Future

Robert Bruninga bruninga at usna.edu
Thu Jul 2 07:18:34 PDT 2009

> Why go with the minimal antenna gain?
> ... any antenna with a 3 db point that exceeds 
> 6.5 degrees is just wasting transmitter power.

I think that would be about a 24 dB gain antenna.  Pretty big
and would take some careful alignment...  Kinda like a realy big
EME array

> Just remember what an Oscar 10 station took 
> to have reliable communications, At Apogee 
> it was only 35,000 miles away, the Moon is ...]
> [250,000 miles]

Which is 7 times farther, squared or 50 times more power (about
17 dB).

BUT one easy way to get gain is to use just a long coaxial gain
cable.  I think it takes about 22 feet of coaxial dipole
elements at 2 meters to give about 6 dB of gain.  So laying down
6 dB gain segments on the rock of the moon is as easy as
unrolling a spool of cable.  Unrolling 8 of these with the right
spacing could yield about 17 dB.

Of course this woiuld only point straight up, so it would need
to be on a moon base in the middle of the earth facing side.
But since there is a lot of interest in moon bases near the
poles where there might be water, then a similar array of layed
down coaxial cable arrays could be phased horizontally to point
at earth.  Actually, just about any direction can  be obtained
with the right spacing.

ONLY problem of course is there has to be someone with legs to
roll out the cables.

Just a thought.

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