Preservation of 144 MHz Polarization over Mountain Ranges

[KP4MD]

My KP4MD 144 MHz WSPR station in Citrus Heights, California was exclusively on vertical polarization (Arrow 146/440 J-pole antenna) from 13 DEC 2015 through 0300 UTC on 25 JAN 2016.  Since that time, my WSPR station has returned to horizontal polarization with the two stacked halo antennas at comparable 20 foot height above ground.

An interesting comparison of spot reports demonstrates a preservation of polarization sense over the 133-136 km signal paths over the coastal mountain ranges between my station and horizontally polarized N6GN and vertically polarized KJ6MKI, both in Santa Rosa, California.  

Carol KP4MD

Remounted 144 MHz Halo Antennas - 24 JAN 2016

 

[Pamela J. Filicky]

Hi Carol - Well you looked at it in more detail than I have, but since you have moved back to horizontal polarization, your signal is down from the vertical.

I'm pointed normally at Santa Rosa, I even pointed directly at you & signal was down. Now my observations are just casual but it seemed that

you were stronger on the vertical..    73 Steve/N6KOG

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[Glenn Elmore]

Interesting data Carol. It very much matches the couple of tests I've made between N6GN and KP4MD by simply rotating the Yagi on this end.  Both times I saw on the order of 15 dB polarization purity which has me amazed.  Who would have thought that this much axial ratio would be maintained across two ranges of mountains. 

A further test would be to split apart the ACS spots from 'direct' ones, that is, aircraft scatter from "mountain scatter".  The two mechanisms seem to have very different characteristics WRT preservation of polarization.

I do not understand the "mountain scatter" mode. Quite amazing.

Glenn n6gn

[KP4MD]

On the other hand, the KP4MD-KI6STW and KP4MD-N6KOG paths showed much overlap between the two data sets.

There were insufficient data from the other station paths to deduce a comparison.

Photo album at https://photos.app.goo.gl/1rHkAirEcJN7u71t7

Carol, KP4MD

[Glenn Elmore]

But isn't that what one would expect if there are two mechanisms, one which preserves polarization and the other which doesn't?

That's why a further study that separated the two, as we could probably do using waterfalls, WSPR spots and PlaneFinder and some effort,  would be worthwhile.

Glenn

On 01/26/2016 04:46 PM, KP4MD wrote:

On the other hand, the KP4MD-KI6STW and KP4MD-N6KOG paths showed much overlap between the two data sets.

There were insufficient data from the other station paths to deduce a comparison.

Photo album at https://picasaweb.google.com/114032640816757126398/144MHzWSPRPolarizationTest

Carol, KP4MD