This one is courtesy of Callum M0MCX. He did the original Excel spreadsheet version. I've converted it for the web. You can view his YouTube channel here

Frequency | Wave Length (M) | 1/4 Wave (M) | Length (cm) | |
---|---|---|---|---|

Current Resonant Freq | ||||

Required Resonant Freq | ||||

* This calculator allows for a velocity factor of PVC coated wire (93%) |