TT group
[I guess this thread is ok since we are talking about using TT rigs on
60 M <grin> ? ]
Channelized,50 W ERP operation is sure going to confuse a lot of average
hams. I'm average and I'm confused. Hopefully the TT reflector will figure
this out for us. <big grin>
I am not close to being an antenna expert but here is my 2 cents.
The manufacturer of the Carolina Windom claims normal gain off the ends on
10 meters but they also claim vertical angle gain on the low angle, DX lobe
for 80 meters.
The Carolina Windom is not really a true classic windom. The "CW Windom"
is an off center fed wire antenna with both a large horizontal and a small
vertical element. The claim is that because of the vertical element's low
vertical take off angle , there will be a larger low angle lobe from the "
CW windom" as compared to a conventional low height dipole. The ads like to
compare the "CW Win" with a conventional dipole at a "typical" low height
of about 35 feet.
Let's think about an 80 meter dipole at 35 feet. How much low angle
vertical lobe will that antenna radiate ? Hardly any ? Now let's suppose
that the manufacturer is telling us the truth and the " CW Win " really
does exhibit a 10 dB gain in it's low angle lobe as compared to the,low
angle lobe of a low conventional dipole. A 10 dB gain over "hardly any" is
still a QRP signal! I'm not saying that the "CW Win" is a bad antenna. It
just might grab more low band DX than a low dipole would, however, it will
not have gain over an 80 meter dipole up 130 feet in the air.
So - 60 meters. I think the FCC is saying we can have a signal comparable
in strength to 50 watts sent to a 60 meter dipole up 1/2 wavelength (over
90 feet) over ground. A Carolina Windom would have no gain compared to a 60
meter conventional dipole up 1/2 wave so there is nothing to be worried
about. The guy who wants to put up a 60 meter Sterba Curtain in his back
yard probably will be in a certain amount of trouble ;-)
73
Bob KB1CIW
[Original Message]
From: Stuart Rohre <rohre@arlut.utexas.edu>
dB of gain on 60m over a dipole! Beware of manufacturers claims, usually
they are quoting for 10m and over isotropic source, and any other way they
Even a 3 element beam only has 5 dB gain Max over a dipole, if that.
<snip>
73, Stuart K5KVH
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