M0UKD calculator to make a Slim Jim or J Pole Antenna.
"M0UKD calculator to make a Slim Jim or J Pole Antenna." Views expressed in this antenna project are those of John (M0UKD). Content and Source: https://m0ukd.com/calculators/slim-jim-and-j-pole-calculator/ Please check link or scroll down to read John's article. Thanks for joining us today. Aloha es 73 de Russ (KH6JRM). Slim Jim and J Pole calculator Slim Jim / J Pole antenna calculator. Frequency MHz Velocity Factor (see text*) vf Actual wavelength metres Wavelength considering velocity factor metres A. Overall length (λ*0.75)*vf (plus gap for Slim Jim) cm (J Pole) cm (Slim Jim) B. Half wave radiator section (λ/2)*vf cm C. Quarter wave matching section (λ/4)*vf cm D. 50Ω feed point. Adjust for 1:1 SWR. (λ/40)*vf cm E. Gap (λ/100) cm F. Spacing - not critical cm Before we start, be prepared to experiment! The calculator will get you close (or spot on if you're lucky), but there are so many variables. You can use an antenna analyser to easi...