CM 144 MHz Halo Antenna NEC model by Carol F. Milazzo, KP4MD
CM Horizontal orientation (using GH command)
CM Frequency = 145.000 MHz
CM Impedance 50 ohms
CM 26-side polygon (40 inch loop with 1.5 inch gap)
CM Simulated good ground
CM Use the high-pass L-network to simulate the gamma match
CE
SY frq=145	'frequency MHz
SY cir=40.00758	'Input loop circumference inches (loop + gap)
SY r=0.5*cir/3.1415926	'Calculate loop radius
SY dia=0.25	'Input loop wire dia. inches
SY rad=0.5*dia	'Calculate loop wire radius
SY n=26	'Input n-polygon of loop + gap
SY h=81.74	'Input height to loop inches
SY g=1.5	'Input gap size in inches
SY gseg=int(n*g/cir+0.5)	'Calculate gap length in segments
GH	1	n-gseg	1e-300	1e-300*(n-gseg)/n	r	r	r	r	rad
GM	0	0	0	0	gseg*180/n	0	0	h	0
GS	0	0	0.0254
GE	1
LD	5	0	0	0	58000000	'1/4 inch copper tubing
GN	2	0	0	0	4	0.01
EK
EX	0	1	(n-gseg)/2	0	1.	0	0	'Feed point
FR	0	0	0	0	frq	0
EN