Topband: superdirectivity

[k6se@juno.com]

Sam, VK4ZSS wrote:

".... but i wonder whether a closer approximation (to superdirectivity,
not supergain) is achievable with receive only antennas. short
non-resonant antennas are entirely acceptable for receiving purposes and
have much lower mutual impedances.

"anyone have any thoughts, or previously looked at this?"
==========
Quite a while ago I modeled four Pennants in a broadside/endfire array. 
The patterns for this array show high directivity, better than a
-wavelength Beverage and considerably better than a 4-square.  The array
I modeled had endfire spacing of 0.25 wavelength and broadside spacing of
about 0.6 wavelength.  This requires an area of 135 feet by 315 feet on
1.83 MHz, whereas a 2-wavelength Beverage is about 1100 feet long.

The broadside phasing was zero degrees and the endfire phasing was 110
degrees.  The azimuth beamwidth of the main lobe was 54 degrees at the -3
B points.  The minor lobes to the sides and rear were all down at least
35 dB from the main lobe.

I'm still waiting for some enterprising Topbander to try this receive
array.

Pennants are small nonresonant terminated loops and modeling indicates
negligible mutuals at those spacings.
73, de Earl, K6SE


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