Re: Topband: : RDF in the real-world
>that a BOG antenna is a tuned circuit not a traveling wave antenna. < Hi Bruce, I am missing something here, can you elaborate on that statement? 73 JC N4IS _ Topband Reflector Archives - http://www.contesting.com/_topband
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: : RDF in the real-world
IV3PRK at HC1PF with the help of friends proved with extensive research and modeling, that a BOG antenna is a tuned circuit not a traveling wave antenna. Please see the IV3PRK research and modeling links at the bottom of my BOG antenna page www.bogantennanotes.html 73 Bruce-k1fz 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. The idea was to quantity what directivity can do for you in practical DXing. Regards JC _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
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: 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: RDF in the real-world
Rick N6RK said: > In this webinar, it was asserted (without explanation) that > for every 1 dB increase in RDF, you get 1.5 to 2.0 dB > improvement in S/N ratio. I've never heard that before > and don't even see how it makes sense. Actually, I don't > even know how you can make generalizations like that > unless you are describing a theoretical QTH with uniform > isotropic noise. I'd like to believe this is true. > Can someone educate me as to why I should believe this? I believe the issue is that RDF is a theoretical calculation comparing the main lobe gain to the overall average gain. The overall average gain essentially results in the assumption that noise is coming in uniformly from all azimuth angles and elevation angles. But in the real-world man-made noise doesn't abide by this assumption, and neither does atmospheric noise. As for atmospheric noise, there was an interesting article about the directional characteristics of atmospheric noise in Radio Science in 2002 (by Prof Chris Coleman, who is a VK5 but I don't remember his call at the moment). Chris even did a plot for me of atmospheric noise coming into W4ZV's QTH on a winter morning, and it was obvious that antennas with the same (or very similar) RDF could provide different SNR improvements depending on where the nulls in the pattern were. 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
