CM This is a shortened vertical antenna design for 20m. The height of the antenna is 12 ft, with a 4.2 uH loading coil at the midpoint. The radiating element is aluminum.  At the top of the antenna is a capacity hat made by a 2-ft-long brass rod that forms a T with the top of the radiating element. There are 16 copper ground radials, each 0.1-wavelength (6.7 ft) long, at the base.
CM 
CE
SY L=12	'radiating element height (ft)
SY G=0.075	'height of radials above ground (ft)
SY NR=16	'number of radials
SY TH=360/16	'radial interval spacing (deg)
SY LR=6.7	'radial length (ft) (0.1 wavelength on 20m)
SY LSEG= 49	'number of segments in radiating element
SY RSEG=25	'number of segments in each radial
SY wrad=#20	'wire radius
SY HL=1.0	'capacity hat wire length (ft)
SY HSEG=4	'number of segments in each capacity hat wire
GW	1	LSEG	0	0	G	0	0	G+L	wrad	'radiating element
GW	2	HSEG	0	0	G+L	HL	0	G+L	wrad	'capacity hat
GW	3	HSEG	0	0	G+L	-HL	0	G+L	wrad	'capacity hat
GW	11	RSEG	0	0	G	LR	0	G	wrad	'radial
GW	12	RSEG	0	0	G	LR*cos(TH)	LR*sin(TH)	G	wrad	'radial
GW	13	RSEG	0	0	G	LR*cos(2*TH)	LR*sin(2*TH)	G	wrad	'radial
GW	14	RSEG	0	0	G	LR*cos(3*TH)	LR*sin(3*TH)	G	wrad	'radial
GW	15	RSEG	0	0	G	LR*cos(4*TH)	LR*sin(4*TH)	G	wrad	'radial
GW	16	RSEG	0	0	G	LR*cos(5*TH)	LR*sin(5*TH)	G	wrad	'radial
GW	17	RSEG	0	0	G	LR*cos(6*TH)	LR*sin(6*TH)	G	wrad	'radial
GW	18	RSEG	0	0	G	LR*cos(7*TH)	LR*sin(7*TH)	G	wrad	'radial
GW	19	RSEG	0	0	G	LR*cos(8*TH)	LR*sin(8*TH)	G	wrad	'radial
GW	20	RSEG	0	0	G	LR*cos(9*TH)	LR*sin(9*TH)	G	wrad	'radial
GW	21	RSEG	0	0	G	LR*cos(10*TH)	LR*sin(10*TH)	G	wrad	'radial
GW	22	RSEG	0	0	G	LR*cos(11*TH)	LR*sin(11*TH)	G	wrad	'radial
GW	23	RSEG	0	0	G	LR*cos(12*TH)	LR*sin(12*TH)	G	wrad	'radial
GW	24	RSEG	0	0	G	LR*cos(13*TH)	LR*sin(13*TH)	G	wrad	'radial
GW	25	RSEG	0	0	G	LR*cos(14*TH)	LR*sin(14*TH)	G	wrad	'radial
GW	26	RSEG	0	0	G	LR*cos(15*TH)	LR*sin(15*TH)	G	wrad	'radial
GS	0	0	0.3048
GE	-1
LD	0	1	25	25	1	4.2e-6					'4.2 uH inductor (midpoint of radiating element)
LD	5	1	0	0	37700000	'radiating element is made of aluminum
LD	5	2	0	0	15600000	'capacity hat is made of brass
LD	5	3	0	0	15600000	'capacity hat is made of brass
LD	5	11	0	0	58000000	'radials are copper
LD	5	12	0	0	58000000	'radials are copper
LD	5	13	0	0	58000000	'radials are copper
LD	5	14	0	0	58000000	'radials are copper
LD	5	15	0	0	58000000	'radials are copper
LD	5	16	0	0	58000000	'radials are copper
LD	5	17	0	0	58000000	'radials are copper
LD	5	18	0	0	58000000	'radials are copper
LD	5	19	0	0	58000000	'radials are copper
LD	5	20	0	0	58000000	'radials are copper
LD	5	21	0	0	58000000	'radials are copper
LD	5	22	0	0	58000000	'radials are copper
LD	5	23	0	0	58000000	'radials are copper
LD	5	24	0	0	58000000	'radials are copper
LD	5	25	0	0	58000000	'radials are copper
LD	5	26	0	0	58000000	'radials are copper
GN	2	0	0	0	5	0.001
EK
EX	0	1	1	0	1	0		
FR	0	15	0	0	14.0	0.025
EN