Hi Lee,
I recently had exactly the same experience with my 160 meter W8JI passive 8-circle array. About six weeks ago intense broadband white noise appeared at my QTH arriving at about 325 degrees azimuth, between the 315 and 0 degree peaks of two main lobes of my 8-circle array. I was able to very accurately determine the azimuth that the signal must have been arriving from by plotting the difference in signal strength on the EZNEC V6+ pattern of the two main lobes. This is exactly the same method used by state of the art HF direction finding arrays that use a huge database of the full hemisphere vs. frequency response of their direction finding antenna to determine the azimuth and elevation angle that a signal must have arrived at to produce the resulting voltages in the antenna The actual location of the source was only 2 degrees off from my calculation, a malfunctioning licensed 10 watt Traveler Information Service transmitter on 1700 kHz two miles from my QTH operated by my local county government. Excellent relationships between our local ham community and the county resulted in the transmitter be turned off within a few hours of reporting the problem to the responsible person. 73 Frank W3LPL ----- Original Message ----- From: "Lee STRAHAN" <k7...@msn.com> To: "JC" <n...@comcast.net>, "160" <topband@contesting.com> Sent: Friday, March 4, 2016 6:00:23 PM Subject: Re: Topband: RDF in the real-world 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-boun...@contesting.com] On Behalf Of JC Sent: Friday, March 04, 2016 9:31 AM To: k...@myfairpoint.net; 'Carl Luetzelschwab' <carlluetzelsch...@gmail.com>; topband@contesting.com 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. Regards JC -----Original Message----- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of K1FZ-Bruce Sent: Friday, March 04, 2016 10:02 AM To: Carl Luetzelschwab <carlluetzelsch...@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 _________________ Topband Reflector Archives - http://www.contesting.com/_topband _________________ Topband Reflector Archives - http://www.contesting.com/_topband _________________ Topband Reflector Archives - http://www.contesting.com/_topband _________________ Topband Reflector Archives - http://www.contesting.com/_topband _________________ Topband Reflector Archives - http://www.contesting.com/_topband