This is an Imperial version of the calculator.
See the main page for more information
.
Slim Jim / J Pole antenna calculator.
Frequency
MHz
Velocity Factor (see text*)
vf
Actual wavelength
inches
Wavelength considering velocity factor
inches
A.
Overall length
inches (J Pole)
inches (Slim Jim)
B.
Half wave radiator section (λ/2)*vf
inches
C.
Quarter wave matching section (λ/4)*vf
inches
D.
50Ω feed point. Adjust for 1:1 SWR. (λ/40)*vf
inches
E.
Gap (λ/100)
inches
F.
Spacing - not critical
inches