Topband: Interesting observation and comment (Skewed Path Vs. Horizontal/Vertical Polarization)

[Don Kirk]

 Hi James,

I left a word out, and I have now added the word into my below text (I
added the word horizontal).

Yes, multipath is certainly a variable, and I'm actually trying to include
something that's not outwardly obvious regarding the directional response
of a receive antenna related to horizontal polarization versus vertical
polarization which is something I had never before considered (I'm not
trying to exclude anything), and I don't recall it being discussed before.
I suspect the signal is changing polarity frequently (probably rapidly) and
probably often appears like circular polarization, etc. so it's a very
complex picture.

Thanks,
Don (wd8dsb)

On Thu, Jun 3, 2021 at 1:30 PM Don Kirk <wd8dsb at gmail.com> wrote:

> Hi James,
>
> Yes, multipath is certainly a variable, and I'm actually trying to include
> something that's not outwardly obvious regarding the directional response
> of a receive antenna related to polarization versus vertical polarization
> which is something I had never before considered (I'm not trying to exclude
> anything), and I don't recall it being discussed before. I suspect the
> signal is changing polarity frequently (probably rapidly) and probably
> often appears like circular polarization, etc. so it's a very complex
> picture.
>
> Thanks,
> Don (wd8dsb)
>
> On Thu, Jun 3, 2021 at 12:57 PM James Wolf <jbwolf at comcast.net> wrote:
>
>> Don't dismiss the possibility of multipath reflections.
>>
>> Jim - KR9U
>>
>>
>>
>>
>> -----Original Message-----
>> From: Topband [mailto:topband-bounces+jbwolf=comcast.net at contesting.com]
>> On
>> Behalf Of Don Kirk
>> Sent: Thursday, June 3, 2021 9:10 AM
>> To: topband <topband at contesting.com>
>> Subject: Topband: Interesting observation and comment (Skewed Path Vs.
>> Horizontal/Vertical Polarization)
>>
>> While playing around with my portable flag that I designed for MF/HF radio
>> direction finding, I noticed something that confused me for about a year,
>> and I finally figured out what's going on which led me to think about the
>> 160 meter skewed path comments I've seen over the years and wonder if some
>> of the observed phenomena is really Vertical versus Horizontal
>> polarization
>> of the received signal and not really a skewed path.
>>
>> There is a local 10 meter beacon that uses an attic dipole and my portable
>> flag as well as my tuned and untuned direction finding loops always
>> indicate
>> the signal is located approximately 350 degrees from my QTH
>> whereas I know this is not correct.   The beacon WA4OTD is actually
>> located
>> 8.6 miles away at a heading of 267 degrees (I'm almost 90 degrees off from
>> the correct herading).
>>
>> Then a few weeks ago I noticed that when my good friend Jay (W9TC) was
>> operating on 20 meters that my portable flag did not point in the correct
>> direction of his house, and he's located 2.8 miles from my QTH and he uses
>> horizontal beams on 20 meters.  I then orientated my portable flag so it
>> was
>> horizontal versus the normal vertical orientation that I use, and "bingo"
>> the portable flag now indicated the correct direction.  I then went back
>> and
>> obtained a heading on the WA4OTD beacon on 10 meters with the portable
>> flag
>> orientated horizontal, and now it points the correct direction (mystery
>> solved).
>>
>> I then went and looked at various antenna models using 4NEC2 in which I
>> looked at the vertical gain versus horizontal gain of the antennas when
>> mounted in their normal orientation, and this explained what I was seeing.
>> Small loop antennas mounted vertical have a maximum horizontal gain that's
>> shifted 90 degrees from the maximum vertical gain direction.  I then
>> modeled
>> beverage antennas and their maximum horizontal gain is shifted 45 degrees
>> from their maximum vertical gain direction.
>>
>> I suspect the polarization of received signals on 160 meters is constantly
>> changing, but wonder if the skewed path observations over the years
>> indicates the polarization of the received signal has shifted to
>> predominantly horizontal versus vertical or a mix of both?  Maybe a crazy
>> thought, but thought I should share my observations with the topband
>> group.
>>
>> I've not really had a problem tracking down typical local noise sources on
>> MF/HF using my portable DF antennas orientated for vertical polarization,
>> and that confirms the many comments that local noise on MF/HF are
>> typically
>> propagated vertically, but thought my observation was very interesting and
>> it unlocked a year long mystery about the local signals that were
>> intentionally transmitted using horizontal polarization that did not track
>> well with DF gear that normally does a phenomenal job.
>>
>> P.S. it took me a while to figure out how to look at vertical gain versus
>> horizontal gain using 4NEC2, but it was sure worth the effort.  Normally
>> 4NEC2 displays total gain.
>>
>> Just FYI, and can't wait for the comments to come flooding in about my
>> crazy
>> idea :) 73, Don (wd8dsb) _________________ Searchable Archives:
>> http://www.contesting.com/_topband - Topband Reflector
>>
>>