Slim Jim and J Pole calculator (American Version)

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