On Thursday, November 6, 2014 7:16:32 AM UTC-6, amdx wrote:

OK, nuff jabbering.
I'll set the rules 15ft tall, designed for 80 meters.
16 radials, base mounted inductor and whatever tophat you desire.
Do the theoretical design find the feed impedance with some efficiency
numbers.
Then compare data to a dipole at 1/4 wave height.

Ready Set GO!

I'll let you all do the actual design and calculating. All of
the software needed can be had free on the web.


Wait, do you have a better idea than a base mounted inductor?

If you use a large enough hat, it really doesn't matter where
the coil is as far as improving current distribution.

How long are the radials?

I dunno.. how much wire is available? How much room?
In general for a limited amount of wire, many short radials
are better than just a few long ones.

Do you want to compare 8 to 16 radials.

Neither one is really enough for top performance over avg ground
with a short vertical.

The tophat needs to survive 80 mile an hr wind.

Use guyed off wire spokes I suppose..

It depends on the path/distance, etc but in general a 1/2 wl dipole
at 1/4 wave is going to smoke most any short vertical of that appx
design. NVIS, HUGELY so.. far DX, might be a toss if the vertical
is performing well. But to really perform well, I'd want at least
60 radials, not 8-16.. In the real world, I generally wouldn't use
such an antenna unless it was all I could get away with.

With ground mount verticals, the shorter the antenna, the more
critical the ground radial system becomes.

On 80m, 99 percent of my jibber jabber is NVIS, and I'd be the laughing
stock of the frequency with such an antenna.
My signal would be quite puny, compared to my normal dipoles and such.
I'd be heckled and tormented endlessly to build a "real" antenna.
I ain't joking either. They can be a tough crowd out there. lol