Topband: Measuring angle

[Tom Rauch]

Milt Wrote:

> The ONLY significant source of noise at Thahtay Khun was Kawtaung,
> Myanmar, 5 miles away, broadside and in full view of the north side of
> the dipole. The dipole was "noisier" than the Beverage to the SSE, the
> only other antenna that could hear the skew path signals.  The
> Beverage was completely shielded from view to Kawtaung, with Kawtaung
> off the left rear of the Bev.

The point I tried to make is without similar polarized antennas and 
an ability to move a null around in elevation without affecting other 
response, we can not possibly have any idea what the wave angle 
is.

Measuring wave angle or polarization with ANY antenna near earth 
is virtually impossible. The reason for this is the earth itself acts 
like a filter. It "tilts" the wave, removing or severely attenuating 
horizontal electric fields (horizontal polarization) along the ground. 
The pattern of any antenna we use is modified by the earth. 

Further complicating the matter is the fact that on receive, it is the 
ratio of noise response to signal response that sets the S/N ratio 
and readability. It is NOT the direction and angle of maximum 
response (gain peak) that is important, it is how well the noise 
response is attenuated compared to the desired signal that matters.

Now if everyone was 40dB out of the noise on all antennas and you 
could watch the S meter from equal gain antennas, clearly the 
loudest absolute signal would indicate direction and perhaps angle. 
But none of us have equal gain and pattern antennas that simply 
have different wave angles, and when digging weak signals we care 
ONLY about the ratio.

I've been trying to figure out how to measure angle here, and the 
closest I can come is with two separate identical large vertical 
arrays in line with the signal, separated by over a wavelength, using 
them as an interferometer. 

The second way is to compare signal level steps between dipoles 
that are at very high heights and progressively lower heights.
  
It almost seems silly to say it, but we can't measure wave angle 
without actually measuring wave angle. That takes acres of 
antennas and antennas that are at various heights up to a perhaps 
a wavelength.

Receiving antennas develop S/N ratio by RATIO of desired signal 
response to noise response, which is a totally different parameter 
than angle of maximum response or gain. One of the last things we 
ever want to do is consider things like TO angle or gain at an 
absolute angle when receiving.

On days when my dipoles work best, I have NEVER found a day 
when a 150 foot high dipole is better than a 300 foot high dipole for 
absolute signal level, although there are days when they are close. 
This leads me to believe the wave angle is not extremely high, but 
of course I can't check every case...only what happens here.

My main point is we have to be very careful creating theories when 
we really aren't measuring anything meaningful to support the 
theory. None of us can define the optimum wave angle, or even 
determine polarization, let alone what the "signal" does to get half-
way around the world.

All we know is which one of our less-than-perfect antennas works 
better for what we are doing at that moment. 
73, Tom W8JI
W8JI@contesting.com