On 6/22/22 11:54 AM, David Gilbert wrote:
Great suggestion. Jim.
I ran HFTA for four conditions at 14 MHz over flat ground.
1. two dipoles at 50 feet and 70 feet
2. one dipole at 50 feet
3. one dipole at 70 feet
4. one dipole at 60 feet
The two dipoles at 50/70 feet show no additional lobes compared to the
single dipoles.
The profile for the single dipole at 60 feet is IDENTICAL to the
profile for the two dipoles at 50 feet and 70 feet except for a gain
difference of 2.7 dB at every point on the curve.
All four curves are on the same plot. The screen shot is available
upon request.
I hope this puts the issue to rest once and for all.
73,
Dave AB7E
On 6/22/2022 11:10 AM, Lux, Jim wrote:
On 6/22/22 7:06 AM, Lux, Jim wrote:
On 6/22/22 12:18 AM, Jim Brown wrote:
On 6/21/2022 7:37 PM, Billy Cox wrote:
So outside of the cautions Dean shared, and used
w
We could do a simple experiment about what HFTA does - I tried it on
my copy, but it's missing some .ocx (ancient version of HFTA from
20th edition) and trying to run it on Win10 under Parallels, which is
sort of a "non optimal" environment.
That is, choose a pair of dipoles (for which it's easy to calculate
the pattern) and flat terrain, and pick some different stacking
distances to see what happens.
say I put a dipole at 50 feet and 70 feet. Run the vertical pattern.
Then run one by itself and the other by itself. The "dual" antenna
configuration should have more lobes (because the spacing is 20 feet)
I was thinking that if you space them multiple wavelengths apart (do it
at 10 meters), then you should get distinct grating lobes. 50 and 70
are about half wavelength, so I'm not sure about grating lobes. two
isotropes 1/2 wavelength apart don't make any lobes.
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