William Warren wrote:
".Bill M" wrote in message
...

Ray Collins wrote:

20 meters. Is it just like AM tower arrays, ground radials as long as
the tower is high at every degree of the compass?

If it were me I'd hang 3 separate dipoles, inverted vees or quarter-wave
slopers off of the tower. The tower shunt feed scheme works fairly well
on 40/80 but I've never had much luck at 20 and above.


What ground system do you use? I've heard various reports about how many
radials are needed, and where/if they must/should be connected at places
other than the center: the only "hard" documentation is on AM broadcast
antennas, and I don't have the budget to buy space next to a salt marsh ...

Bill



I had a 40 meter vertical with 60 radials that really kicked butt.
Outperformed a nearby ham's 3 el "contest station" yagi in most every
case for the real long-haul stuff.

My son and I put the radials in progressively - the ant was located in
the bush in rocky terrain and was nothing more than a push up TV mast
balanced on a coke bottle and guyed with nylon rope. After about 2
dozen radials the difference wasn't really noticeable and this jives
with results I've heard from other people.
A 20 meter vertical (those push up masts are frequency agile-hehe) at
the same location was a dud compared to an A3 on a 15 foot mast further
down the hillside.

I shunt fed a tower once (60 ft with triband quad on top), no particular
ground system. Many of these schemes involve 'tuning' the ground lead
in order to get them to work. I got it to work on 40, can't recall how
80 acted but it wasn't near as good as a 1/4 wave sloper from the top of
the same tower and it kept the shack hot with RF. Again, it was a dud
on 20 and above. My guys were grounded and that seems counter-intuitive
for a vertical radiator.

I'm of the mind, based on my experience, that ground-mounted 20-15-10
stuff just isn't very effective compared to say a ground plane scenario
where the antenna can be elevated. And then that raises the question
whether or not an inverted vee at the same height as a ground plane is
more effective. I'm not sure there's an answer to that question but
vees and dipoles are easier to construct at the top of a tower :-)

-Bill M