On 10/14/21 6:03 AM, Roland Turner via groups.io wrote:
On 14/10/21 8:14 pm, Joe Smith via groups.io wrote:
Some background my be found at these two links:
/g/NanoVNAV2/topic/t_check_with_labview_nanovna/85036914?p=,,,20,0,0,0::recentpostdate/sticky,,,20,2,0,85036914,previd=9223372036854775807,nextid=1630672957048663752&previd=9223372036854775807&nextid=1630672957048663752
OK, so a cost-and-integration-effort vs. isolation tradeoff. Interesting. Thanks.
I very rarely want to be able to measure all four parameters, but did have an experience recently where the iterative process of tuning a duplexer meant many dozens of cable changes during the process and hands that were sore for days afterwards. A transfer switch ¡ª or two analysers ¡ª would have been less painful. Although in that particular case the isolation requirements were so high that a suitable transfer switch would indeed have been unworkably expensive and NanoVNAs would generally not have been sensitive enough.
Getting what one pays for...
Exactly... It's what things like 3 and 4 port analyzers were developed for - Simultaneous measurements, with high dynamic range, without needing to cable/uncable or do the math to convert multiple 2 port measurements to N port measurements, etc.
Tuning a ferrite circulator, especially with multiple ferrites, would be another "it would be nice to have a 3 port analyzer" application.
I need to build a little circuit which has a very different S11 and S22 to try it out - a single LC low pass would work nicely. Or even an asymmetric resistive divider (1 series R, 1 shunt R)
But more curiosity than anything else.? The idea of multiple simultaneous measurements (no relays) is intriguing.? One could build a N port analyzer with N sources and N^2 receivers, and choose the stimulus frequencies carefully so that no two are at the same frequency at the same time.? If the receiver is a wideband SDR, then conceivably, the N^2 receivers are implemented in only N pieces of hardware, and the selectivity is in software. With 16 bit ADCs and some averaging, one might be able to get 80-90 dB dynamic range, or better.
