Malcom

It seems that you've got a problem on your hands. The base station must
cover the hemisphere and have good gain at or slightly below the horizon. I
suspect thats a very difficult pattern to produce with linear polarization.
A QHA (helical) antenna might be an interesting antenna to try. But, it
wouldnt be an easy antenna to develop and construct, like the J-pole or
discone.

Jerry






"Malcolm Austin" wrote in message
...
Hi Jerry,
yes had thought of going directional, but have some small
problem. Him up stairs, keeps changing the wind so we have to move the
winch about the field. Some times this can be by 180 degrees ! So we are
restricted to omni-directional...

Cheers, Malcolm...


"Jerry Martes" wrote in message
...

"Malcolm Austin" wrote in message
...
Hi,
I have an interesting problem which I'd like to put to the
newsgroup
for idea's. Our club (gliding by the way) uses just a few frequencies
to
transmit (AM) and receive on.

The main freq' is 129.975, but we go down to 129.900 and up to
130.400.

We need some new antenna's but I'm wondering what would be the best.
Currently we use a quarter wave set for 129.975, but this is I'm
afraid
just
cut to a length (the lads are pilot's and not Ham's !!)

The quarter wave of course is good in one respect that we are all
hopefully
up in the air so the high angle of radiation helps. It would be good
though
to improve the signal to our winch which is just 950 metres away (3100
feet
for some!) but over the hill so to speak, so not line of sight. We
struggle
at times on our max 1 watt output to hear each other.

I'm wondering what I can build that will help this low angle but leave
the
high angle still there. Also it would help, to have the VSWR band
width
with us and not against us on all the frequencies. For the winch we
have
limited height available on the top due to hangerage restrictions. If
I
build something big and solid, some one is sure to forget and rip it
off
going into the MT hanger. Our base end is a good old English double
decker
bus, so we have a good ali ground plane some 20 feet in the air. None
directional capabilities are of course required as we fly 360 degrees
around
the club.
Any thoughts out there?

Many thanks,

Malcolm - Radio Ham and Glider pilot.

Malcom

I'd suggest that the antenna at the winch can be made more directional
without increasing its height. But, you've probably thought of that.
It
would seem to be a good place to try a simple, small Yagi at the winch.

Jerry