> Pretty funny -- I wasn't sure what Tom meant by a
"Marconi", so I went to
> the ARRL Antenna Book to look it up, and the only
reference in the index
> was to the guy who did those early experiments -- *that*
Marconi. ON4UN's
> book had no index reference to Marconi at all.
...back to Handbook indexes again! These are commonly used
definitions.
Marconi refers to an antenna that works against ground.
Hertz antennas would be in the family of antennas that are
ground independent and self-resonant.
> From context, I infer that Tom is talking about
base-feeding one mobile
> whip, as originally intended, and placing it over a good
ground
> plane. Correct? In that case, wouldn't another, more
efficient mobile
> antenna be a better choice?
Probably, but the issue is complicated. Over a really good
ground the coil type could make a big difference.
Over a really poor ground the coil location makes a big
difference, and the coil loss is much less important.
With a Marconi you have one loading coil adding loss. A
Marconi also has wider bandwidth, all things equal double
the bandwidth. If you keep the overall height the same, you
have the same or higher radiation resistance (depending on
coil location).
Look at the short coil loaded verticals (or dipoles) and
compare. Any of the "short halfwaves" or similar feedpoint
in the air (GAP, MFJ, whatever) have a really tough time
against a regular old trap vertical with a modest ground. I
think the Vertical Antenna Comparison by Champion Radio has
tables that reflect this, I know QST reviews and real-life
measurements do. This is also why Inverted L's on 160 and 80
are so broad and work so well.
If it were possible, I'd install the best ground I could and
use a long mast and add a capacitance hat at the top.
DX Engineering makes a hat that fits the Hustlers and allows
a 40 meter resonator to be used on 80. You get much better
efficiency and much more bandwidth. I don't think I'd use
80M Hustler resonators either Pete.
73 Tom
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