[TowerTalk] array matrix measurements

[jimlux]

Rudy Severns wrote:
> I've made these kinds of matrix measurements several times since I got my 
> hands on a VNA.  It's not too hard and actually a lot of fun.  I've found 
> that if I've been careful, the reciprocal measurements are usually within 1% 
> or better.  This holds true even when the values themselves are really 
> strange, as they can be when there's a parasitic radiator coupling into the 
> array.
> 
> Usually I do the measurements using only impedance measurements which is 
> very straight forward but occasionally I'll use the transmission mode and a 
> current transformer to do a direct measurement of coupling.  Both ways seem 
> to work fine as long as I pay attention to the details.
> 

which VNA are you using?

I've been using Tom's version sold by TenTec.. I've been pretty happy 
with it (especially now that there's CocoaVNA for the mac), although I 
don't have any strong interferers, either, so the "wide open" receiver 
isn't an issue.

I suspect that almost any of the new crop of analyzers/VNAs would give 
good (symmetric) results on matrix measurements. It's trying to do it 
with the older  MFJ-259 or Autek units that would be challenging, 
because of the dynamic range issues, I suspect.