RadioBanter - View Single Post

October 23rd 05, 06:02 AM

On Sat, 22 Oct 2005 00:33:19 GMT, (Mark Zenier)
wrote:

In article , SR wrote:
The last few evening the moon was almost full and the evening sky was
fairly clear here in New York. I then transmitted on my CB but no DX
only locals.

I read something somewhere that mention about Moon Bouncing. Meaning
that a signal can travel far. But I am not sure if that is true.

It's a VHF and microwave thing. You actually illuminate the Moon
with enough power that another station back on Earth can pick up
the reflection. But that requires an antenna that can focus most
of your power on the Moon, a target only 1/2 degree across. Hams,
with 1 kilowatt, can get morse code and slow digital signals (on the
higher bands).
I believe it was first done in the 6 meter band in the 1950's/

Before satellites the Defense Department was able to send several
teletype channels at at time, maritime mobile. That was with a big dish
and probably 10's of kilowatts. (The best description of using that
equipment, that I've seen, was in a description of the incident where the
USS Liberty, the radio intelligence ship, was attacked by the Israelis.
In the Atlantic Monthly about 10-15 years ago, as I remember).

Yes, but that wasn't moonbounce, it was tropo scatter. YOu can only
use Moonbounce when the moon is visible to both ends. Troposcatter
works just about anytime, anywhere. The change in permittivity at the
top of the toposphere will actually bounce a tiny portion of the
microwave signal back down quite reliably. You can get about 600
miles that way. But you need the sort of big dish, and tens of
kilowatts to do it reliably. Only the military could really afford to
use it.