[Elecraft] K3 diversity phase drift

[Alan]

Hi Dave,

Have you  given any thought to using this technque to measure the 
polarity of the incoming signal?  One receiver input would go to a 
horizontal dipole and the other to a vertical dipole, with the two 
dipoles co-located (feedpoints at the same location).  It could also be 
done with two Yagi antennas mounted on the same boom.

If you can measure the phase of each signal as well as the amplitude, 
the polarity can be calculated with a little trigonometry.

This is something i've wanted to do for years "when I get time". :-)

Alan N1AL


On 4/9/2026 6:43 PM, David Gilbert via Elecraft wrote:
>
> Hi, Mike.
>
> I haven't done any searching, but I'm sure that such studies have been 
> made ... probably many decades ago.   A good friend of mine told me 
> that a long time ago he was a consultant for the Army on a project 
> that used an array of several antennas to track instantaneous changes 
> in arrival angle using phase determination. He said that significant 
> changes could be seen in fractions of a second, but I wouldn't be 
> surprised if they were also experiencing multipath diffraction patterns.
>
> In my case, I think several factors are at play.  I'm using two short 
> (non-resonant) horizontal dipoles 18 feet high spaced about 12 feet 
> apart that are both broadside to WWV, and I'm using a really narrow 
> bandwidth on the K3 to filter out the sidebands so I get only a mostly 
> clean carrier.  Given the results I see, I think these are the 
> possible effects:
>
> 1.  Simple multipath reflections due to ionospheric propagation effects.
> 2.  Reflections from the sloped ground beneath the antennas (I live on 
> a hillside) that would have different effect with different arrival 
> angles ... AND different effect caused by #1 above.
> 3.  Reflections from surrounding terrain.  I not only live on a 
> hillside with a mountain range to the south and west of me, but there 
> is a deep (50 foot deep, 120 foot across) ravine roughly 100 feet to 
> the south of the two dipoles.
>
> I don't think it is possible to accurately model any of that unless it 
> was possible to actually measure and plot a ground conductivity 
> profile of the entire area that would show where the actual RF ground 
> plane is.  The sides of that ravine show how variable the earth is 
> here ... soil in some places, iron-based rocks in some places but 
> limestone or quartz in others, and rocks varying from the size of an 
> orange to the size of a garage.
>
> I have to admit, though ... even if I can't get unambiguous numbers 
> for arrival angle, the application accurately displays the relative 
> phase between the signals that are coming from the two dipoles and 
> it's rather fascinating to see the rapid and significant changes over 
> time.
>
> The application may be better suited to displaying the azimuth angle 
> of a signal ... presumably using vertical antennas.  I suspect that 
> there is less multipath propagation azimuth-wise than there is 
> elevation-wise ... but I could be wrong about that as well.  ;)
>
> 73,
> Dave  AB7E
>
>
>
> On 4/9/2026 10:18 AM, Michael Carter via Elecraft wrote:
>> Hi Dave,
>>
>> I've been interested in your experiments since you first posted news 
>> of them and the app you developed for angle-of-arrival estimation.  
>> Your latest post really piques my curiosity.  Is there new science to 
>> be uncovered for the effects you describe as anomalous, or is there 
>> professional academic literature that already has reported such 
>> effects?  I have not ventured into that literature, but would be 
>> surprised if some ionosphere scientists had not conducted similar 
>> experiments.
>>
>> Thanks for a very interesting thread, and keep the reports coming!
>>
>> 73,
>> Mike, K8CN
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