[amsat-bb] Re: using a microsat as a potential high altitudeVHFreflector

[i8cvs]

----- Original Message -----
From: "andy thomas" <andythomasmail at yahoo.co.uk>
To: "amsat" <amsat-bb at amsat.org>
Sent: Thursday, October 29, 2009 11:04 AM
Subject: [amsat-bb] Re: using a microsat as a potential high
altitudeVHFreflector

> I still think that a large unfolded and/or (partially?) inflatable
structure of reflective material structured as resonant reflectors could be
an interesting passive reflector of ham frequencies if it was placed on the
Moon. It would be easier than a powered active repeater.
>
> I know about moonbounce obviously and the laser system left behind by
Apollo.
>
> 73  de andy G0SFJ
>

Hi Andy, G0SFJ

I have many doubts about your idea because the surface of the moon
as seen as a radar target is large as 9.45 x 10^12 square meters and is
isotropically backscatterig only the 7% of the power of radio waves
incident over it for the frequencies ranging from 144 to 1296 MHz 

Actually EME is made under the above conditions like the moon was
large only 9.45 x 10^12 x 0.07 = 6.615 x 10^11 square meters but
made with a material totally reflecting isotropically the 100 % of power
incident over it.

If now we assume that hypothetically you can put over the moon a
passive inflatable structure of reflective material with 100 % of
reflectibility then to made EME with the same actual moon-bounce
results the above inflatable surface would be made large as
6.615 x 10^11 square meters i.e. it's impossible.

If such thing would be possible the diameter of the above inflatable
structure if placed at the distance earth-moon it would be seen in the
sky sottending an angle of 0.14 degrees  but actually the moon is
sottending 0.5 degrees so that imagine how big would be the above 
inflatable reflector on the moon and figure out if it would be easier
to made instead to use a powered active repeater.

73" de

i8CVS Domenico