"Hal Rosser" wrote in message
.. .

"ke6cqk" wrote in message
...
Is there a good way to connect a 2 meter radio to an antenna on a
nearby hill without using a cable? The radio is down in a small
valley with bad propogation and putting the antenna about 1,000 feet
away should work. Thanks.

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.

To continue - I recall an article (I believe it was in QST) that described
using 2 rhombic antennas (uhf) at a mountain top. One was pointed to a
distant repeater, and the other was directed into the valley where they
could 'finally' hear and talk to the repeater.

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.

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.

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
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.

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

"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

On Sat, 26 Mar 2005 10:10:07 +1100, "nana" wrote:

Or you could try hiding a small dualband HT in crossband mode with a small
solar panel on a hilltop and working through it.

HT might overheat significantly if on full power for an extended
period of time. Such as during a net.

If you are just transmitting yourself that's nowhere near as
continuous duty as cross band repeating.

Tony