On 9/4/21 8:05 PM, Wes wrote:
For an illustration try this:
http://www.cuminglehman.com/wp-content/uploads/Introduction_to_Antenna_Test_Ranges_Measurements_Instrumentation.pdf
and look at the figure on page 4. This shows the usual antenna range
situation where the test antenna is receiving a signal from a point,
or small aperture source. This is how I would run this comparison. I
think, but do not know for sure, that I would use the larger dimension
of the vertical(s) as the "D" in the equation. The idea is to have a
plane, or near plane, wave over the whole aperture of the test antenna
in both directions. Note that some antennas, Yagis for instance, can
have an effective aperture larger that the physical aperture.
Wes N7WS
But that's the 2D^2/lambda - and that comes out strangely small. And
it's not effective aperture (that's more about voltage/power at the
feed) - this is about the physical optics.
D =30m (across the 4 square diagonally) is almost certainly bigger than
the height of the 80m elements (20m?)
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