The Gladiator verticals are center loaded verticals, 21 ft tall for 80M
as I recall.
Top loading is the most efficient method of loading. (Cushcraft/MFJ)
Base loading is the least efficient means of loading (HF2V)
Center loading is somewhere in between. (Gladiator)
The shorter the antenna, the lower the radiation resistance and therefore
the lower the efficiency. A 20 foot high TOP loaded vertical models at 8
Ohms radiation resistance above a perfect ground. I would expect a
center loaded vertical to be less.
I do not have the data sheet for the Cushcraft 80M vertical but my
recollection is
that it is closer to 30 ft tall, top loaded, and can be switched from CW
to SSB.
Believe it is priced in the $300 range.
The MFJ-1792 (?) 80/40 vertical is full size on 40M, has a 40M trap and a
capacity hat for top loading on 80M. Bandwidth on 80M is somewhat
narrow. (I tune my 80M antennas for CW and use tuners for SSB. Don't
know how well this would work with this antenna). Price is $160.
Requires guying.
One of the best and simplest 80M antennas is a Vertically Polarized Delta
Loop. An equilateral loop for 80M is 80 ft high but the base can be
spread out to reduce the height requirement. Feed 1/4 wavelength down
from the apex on one side with an odd number of QUARTER wavelengths of 75
Ohm cable (RG59 wil handle 1KW just fine). I would suggest nothing lower
than a 50 ft high support. When the bottom wire is close to the ground,
additional loading is present and the loop should be made 3.5% shorter
than the 1005/F formula length. Whenever I ask a particularly European
what his antenna is, a Delta Loop is the most frequent answer. WA4CTA,
WZ4F, KZ4V have all found them to be quite effective.
de Tom - N4KG
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