[NLRS] Isosceles Triangular omnidirectional 6-meter loop antenna impedance matching

[JamesDuffey]

Carl - Yes, the gamma match is a poor choice for matching at VHF. 

I am not sure what is in Dale’s feedpoint black box, but if I were to make an antenna like this, I would make the antenna a bit longer than a half wave, so the feedpoint impedance is a bit inductive. Then, cancel out that inductance with series capacitors, preferably mica, in each leg. You should probably spend some time modeling before implementing it. 

Another idea, and probably more useful if the current antenna is shorter than a half wave, which it probably is, is to use an inductive match, either a hairpin patch or a tapped inductor across the feedpoint. 

A common mode choke is always a good idea. 

Let me know if you have any questions. - Duffey

James Duffey KK6MC
Cedar Crest NM

> On Jul 20, 2021, at 09:37, Carl A Estey <carl at esteys.net> wrote:
> 
> Hello all;
> 
> At the tailgate swap fest a few weeks ago I bought a loop antenna for 6-meters.that looks similar to the PAR Electronics OA-50.  I tried the antenna yesterday and it works poorly.  There is a slight decrease in SWR at 50.5 MHz but it does not get below 3:1.  
> 
> I discovered that the antenna uses a gamma match as compared to the PAR which uses some sort of sealed mystery “matchbox”.  I suspect that this mystery tuning box has some sort of current choke and may be a 4:1 impedance matching choke.  
> 
> Does anyone know what is in this mystery tuner and have suggestions as to how I might make this antenna work?
> 
> 73
> Carl WA0CQG
> carl at esteys.net <mailto:carl at esteys.net>
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