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Old March 25th 05, 11:42 PM
Hal Rosser
 
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"nana" wrote in message
...

You can make a "passive repeater". This requires 2 directional

antennas.
At the top of the hill, hook up both antennas (to each other) and aim

one
at
"the world" or the repeater
and aim the other at your house. run a cable between them.

When they built the Georgia Railroad Bank Bldg in Augusta (years ago)

the
phone company had to install a passive repeater on it because the
building
interrupted line-of-sight for a microwave shot.

I've never tried this myself, but I've heard that the technique is very
useful in mountain terrain.


Passive repeaters are used at microwave frequencies all over the Snowy
Mountains in Australia. They are the size of drive-in theatre screens with
tilt adjustments.

*************************
Cool - I guess dishes that size must have lots of gain.
*****************

Remember, when the signal is retransmitted there is an additional path

loss
of something like 130dB. The signal being received by the repeater antenna
must be very strong or the transmit antenna will only have a few nanowatts
to deal with.

***********************
I assume the signal is being retransmitted because of obstructions in the
line of sight,
so they're not done as a whim. Both antennas need to be high-gain, I
assume, because
the signal is not being amplified electronically. The loss of 130 db is hard
to believe. What about the 'gain' from the receiving antenna and the 'gain'
of the retransmitting antenna ? I concede some loss in the cable connecting
the two, but not 130 db, is it?? The loss would be more when it hit the
mountain obstacle, right?
***************************
You would be advised to do a few path loss calculations before putting in

a
lot of effort which may be wasted. The exercise is well worth it as the
process is very educational. You will need to know either the available

**********************************
If I were the original poster, I would probably try it
***********************************
signal strength from the distant repeater at your proposed site, or it's

ERP
and distance. Also, your distance and ERP up to the remote site. Then you
have a few figures to begin working with.

*******
But its more fun to go ahead and build it and see if it works.
I once argued with a guy who told me hot water would freeze faster than cold
water.
I explained the differences in btu needed and even dug out the old slide
rule with a bunch of supporting calculations.
--then we just 'tried it' - I was wrong - he was right - and neither of us
could explain why
*********************************
Or you could try hiding a small dualband HT in crossband mode with a small
solar panel on a hilltop and working through it.

Nana