Estimate starting dimensions for VHF/UHF J-Pole and Slim Jim antennas. The values are practical build starting points and should be trimmed in the field.
Wavelength:
Main section:
Matching stub:
Suggested feedpoint:
Feedpoint tuning window:
Open-gap / spacing:
Use the feedpoint as a starting point, then move the tap or clamp a few millimeters at a time to minimize SWR.