NEC-LIST: Modeling loops

Firmly-entrenched lore gives the perimeter of a square loop at resonance to be
1005/f(MHz) feet. NEC-2, NEC-4, and MININEC all agree quite closely with each
other, but none show this value. (MININEC requires very short segments at the
corners for this analysis.) For AWG 12-16 wire at 10 MHz, the programs show a
free space resonant perimeter length of 1031-1034/f. This of course changes with
proximity to ground and loop shape, but I couldn't find any reasonable
configuration which would bring the model resonant perimeter lower than about
1020/f.

While two or three percent is good accuracy, an error that size is more than
enough to significantly affect the pattern of a parasitic array if the error
occurs in a parasitic element.

Does anyone know of any good measurements of the impedance of a nominally full
wavelength perimeter loop, or of the pattern of a quad or similar parasitic
array of loops, for comparison to NEC results?

Thanks!

Roy Lewallen
Received on Wed Dec 04 1996 - 09:32:10 EST