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Built a free tool that diagnoses SWR problems from two numbers

cbradiohq

New Member
Aug 7, 2026
1
3
1
41
Got tired of seeing the same "my SWR is high, what's wrong" threads with 15 replies of guesswork, so I built something that actually gives a straight answer.

You plug in your Channel 1 and Channel 40 SWR readings, and it tells you exactly what's going on — antenna too long, too short, or a grounding fault — plus what to actually do about it. No account, no app, just numbers in, diagnosis out.

[SWR Doctor →] (https://cbradiohq.com/#swrlink)

Built it because I was tired of chasing that answer down manually every time, figured other people probably were too. Free, no catch. Let me know if it nails the diagnosis or if you run into an edge case it doesn't handle — still refining it.
 

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The SWR readings I entered suggest resonance is closer to ch40 than ch1 which would mean the antenna is too short, not too long. Antennas get shorter with higher frequency so this is 100% backwards. Shortening an antenna will raise its resonant frequency, not lower it.
 
I was trying to keep it simple, but yea, I used the term resonance incorrectly. "Resonance", as we all know, is a lack of reactance (resistance only) and has nothing to do with what resistance (or SWR) that point occurs at. The best SWR often occurs where jX is not zero. I used the term resonance incorrectly and I thank you for pointing that out.

I also wanted to add that not all antenna SWR plots are nice parabolas. Sometimes variables like ground planes, matching networks, mismatches and common-mode currents can all cause reflections and waves to superimpose. The SWR plot can be wavy which would entirely invalidate a tool like this that is based on just two readings.
 
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Just remembering that the higher the frequency, the shorter the wavelength, the shorter the radiating element, tells one all the info that's needed. Especially if all one is tuning for is SWR.
 

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