Hi Carl
Yes, the concept is assuming equal density noise spread uniform. However there
air point everybody wants to hide. Vertical polarized antennas based on phasing
elements does change directivity and does have interaction with others vertical
elements. It is hard to measure it because you cannot turn the antenna for
different directions to measure it.
The Bog is a travel wave antenna, and it is based on the difference in velocity
on the ground and on the wire, it does not interact or deteriorate with other
vertical structures like the flags. The SAL antenna is really a K9AY very
complicated but same directivity and RDF, the TX antenna does deteriorate the
pattern and you can’t see the same reduction in signal to noise ratio because
the REAL RDF is no longer the same as the CALCULATED RDF. The BoG performance
is more predictable, like the beverages and the real RDF is close to calculated
RDF.
Like you see in the diagram when I remove the detuning skirt from my TX
antenna, with that tiny yellow jumper grounding the skirt, the radiation patter
of my excellent VWF become useless without detuning the TX antenna.
The Webnair is limited to one hours and there are interesting aspects of each
antenna that deserved more time to elaborate, maybe next time with dedicate one
hour for each type of antenna.
The idea was to quantity what directivity can do for you in practical DXing.
Regards
JC
-----Original Message-----
From: Topband [mailto:topband-bounces@contesting.com] On Behalf Of K1FZ-Bruce
Sent: Friday, March 04, 2016 10:02 AM
To: Carl Luetzelschwab <carlluetzelschwab@gmail.com>; topband@contesting.com
Subject: Topband: RDF in the real-world
I agree. There are times, especially in disturbed condx, when my BOG antennas
are "head and shoulders" better than my other antennas.
73
Bruce-K1FZ
www.qsl.net/k1fz/bogantennanotes.html
I can't vouch for JC's numbers (his numbers may be QTH specific), but
the concept is believable since the theoretical assumption of isotropic noise
falls apart in the real-world. My BOG *at times* gives much more of an SNR
improvement than the SAL-20 (using measurements on a calibrated S-meter) in
spite of the small difference in RDF between the BOG and SAL-20.
Carl K9LA
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