[TowerTalk] S21 to Rp & Cp - Equivalent Circuit

Jim Brown jim at audiosystemsgroup.com
Fri Jan 12 15:29:13 EST 2018

Going back to Maximo's original question (more than a week ago, I think) 
he was using an Anritsu instrument to measure the choke, and the 
available options for displaying data do not include the ability to 
perform math to get choke Z on screen, which is his objective.

Granted that he already has the Anritsu, it does require the export of 
data to a spreadsheet to get choke Z.  I suggest that, given it's low 
cost, high quality, and math capabilities to compute choke Z from S21 
data and display it on screen, he consider purchase of the VNWA 3e from 
SDR Kits in the UK. The design is by DG8SAQ, and both he and the SDR 
Kits people support it on a Yahoo reflector. The unit is NOT a kit, it's 
fully built and tested, and sells for 475 pounds with one short cable 
and Rosenberger calibration kit.


73, Jim K9YC

On 1/12/2018 7:50 AM, Máximo EA1DDO_HK1H wrote:
> I thought Maximo was trying to derive R and X from S21 measurements, not
> S11 measurements - at least that's what his Subject line suggests.

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