Hi again,
First of all, the Sommer Verticals are weird beasts indeed in that aren't really
verticals (in the sense radiator against a counterpoise) at all.
The closest I can describe them (shortly!) is: Very narrow terminated loops,
oriented vertically. They are more closely related to the T2FD, the Beverage and
the terminated loop (the so-called wave-antennas), than the vertical GP. Alf
Sommer tries to explain the principles on his WEB-site
(http://www.sommerantennas.com/25work.html). One side of the loop is eletrically
very short, and formed as a set of four radials, all of different, non-resonant,
lengths. He does give a suggestion for improving 40m properties by tying on a
tuned radial for 40m - I haven't tried this yet.
The next thing to try for me will be to move the antenna around, to see what
influence surrounding buildings etc. have.
73s de OZ1PIF, Peter
A comment to Jim: I do not believe that going beyond 4 radials on an elevated
system, is going to make any significant difference!
>On 20m, which should be a >natural< frequency for it, it's more that one
S-unit
>down compared to my 20m GP (mounted at the same height, 15' above ground),
and
>the "tuning loss" is about 25W for 100W drive.
Aloha Peter,
I also have an elevated 20 meter vertical, a monoband Gladiator. It's
base is up about 12 feet or so above the surrounding vines, typical
low "jungle" growth which grows incredibly fast out here! Anyway,
it has elevated radials, only four now. I have compared it to my
Mosley 4 element triband beam, a TA-34XL; listening to the
NCDXF beacons scattered about the globe on 14100 kHz. I
find that usually, if I can hear a beacon on the beam, I also
can hear it on the Gladiator, but usually softer by from 1
to 2 S meter units on my FT-1000. If I can only hear the
100 watt level from a distant beacon, say the one in Kenya,
I still can usually hear that 100 watt signal on both beam
and vertical. From this I surmise that they are no more
than 10 dB apart in "sensitivity".
I have been told that if I were to increase my elevated radial
count from 4 up to 36 or so, I might pick up another 4 or at
most 5 dB. That is a big job adding 32 more elevated radials, hi!
Do you have any comments on my situation. And I am sorry
about your experience with the Sommer. I had a look at
their web page, and was a bit put off by the apparent
design. Looked like just a wire running up a support
pole, and some other fooling around, was what it was
all about. And no real performances data at all. I emaild
to them for more info, they never responded.
73, Jim, KH7M
On the Garden Island of Kauai
Hawaiian Islands
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