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" <k7tjr@msn.com>
To: "JC" <n4is@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-bounces@contesting.com] On Behalf Of JC
Sent: Friday, March 04, 2016 9:31 AM
To: k1fz@myfairpoint.net; 'Carl Luetzelschwab' <carlluetzelschwab@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-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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