"Richard Clark" wrote in message
...

Hi Ken,

Research the experience of Mobile HF designs. You will need to invest
in the equivalent metal presented by a car (reasonably done through a
ground mat of similar foot print) to act as the ground/reference which
allows these antennas to work.

It has been long established that a resonating coil about 8 feet up
this permitted 10 feet, with a large top hat built out at the top
would be the most efficient. This is the optimal solution to the
restrictions you have been placed in.

As for your wrap around antenna; you show a clever intuition, and you
may wish to use this 10 foot allowance to build it out, at that height
instead of snug against the building. My hunch is that it won't make
much difference (don't take down the original), but it gives you room
to experiment if the building super will allow you 3 or 4 points
elevated that same 10 feet. A smaller loop may aid in those bands
that are just not performing. If you can get away with 2 points, you
can look to top loaded verticals that go beyond the top hat (in other
words, a top hat that requires extensive mechanical support).

73's
Richard Clark, KB7QHC

After thinking a bit I'm leaning on the idea of just putting up a
10' mast and using it to support a Van Gordon all bander. My
building is 54x40 and 25' tall so by my math the 135 foot all
bander would overhang on the ground just a bit. There are trees
on the corners of the building so that's where the ends of the
antenna would go.

My current antenna would stay for comparison reasons.

Now - on my 153'2" dipole, I feed it with 12' of rg58 and a
9 turn, 2-5/8" dia coax loop at the feedpoint. Should I
duplicate this feedpoint for the 450 ohm ladder line of the
Van Gordon antenna or should I buy a balun? And if I buy
a balun, what ratio?

Thanks for your help, OM!

73's de Ken KG0WX