Topband: RDF in the real-world

Lee STRAHAN k7tjr at
Fri Mar 4 13:00:23 EST 2016

Hello JC and others,
   I must take a little issue on being able to measure the vertical arrays. While it may be true that it is hard to measure, you can indeed see the pattern quite well by looking at different stations and switching around the compass. It does not take long before you can observe the pattern and can tell that there may be something wrong with it. In my case there are 2 lobes on the side of the patterns of my best antennas and you can certainly see the results for even slightly skewed signals because of them.
   I recall an instance a few years ago where W0FLS was able to DF a long standing carrier on 160 within 1 or 2 degrees using his 8 circle and his observations about pattern.
  So it is like your RDF and signal to noise description, it is not easily measurable but observable. Yes, Directivity rules.
Sorry I missed your webinar due to other commitments. I will be able to view it when it is archived.
Lee  K7TJR

-----Original Message-----
From: Topband [mailto:topband-bounces at] On Behalf Of JC
Sent: Friday, March 04, 2016 9:31 AM
To: k1fz at; 'Carl Luetzelschwab' <carlluetzelschwab at>; topband at
Subject: Re: Topband: RDF in the real-world

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.


-----Original Message-----
From: Topband [mailto:topband-bounces at] On Behalf Of K1FZ-Bruce
Sent: Friday, March 04, 2016 10:02 AM
To: Carl Luetzelschwab <carlluetzelschwab at>; topband at
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. 

       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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