[TowerTalk] S21 to Rp & Cp - Equivalent Circuit

Máximo EA1DDO_HK1H ea1ddo at hotmail.com
Fri Jan 12 15:36:49 EST 2018

Hi Jim,

I agree, the VWNA is at this time best VNA option up to 1 Ghz for bench use (with computer).

The reason I don´t have a VWNA is because I need a VNA to use it in the field as well, with no computer.

I like to sit on the soil, or on the roof, and test the antenna. In that situations a self-capable VNA is needed and Anritsu is very reliable (high dynamic range and robust to in the band interference).

Thank you anyway.

73, Maximo

De: TowerTalk <towertalk-bounces at contesting.com> en nombre de Jim Brown <jim at audiosystemsgroup.com>
Enviado: viernes, 12 de enero de 2018 20:29
Para: towertalk at contesting.com
Asunto: Re: [TowerTalk] S21 to Rp & Cp - Equivalent Circuit

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.

DG8SAQ VNWA 3 and 3EC Models - SDR-Kits<https://www.sdr-kits.net/index.php?route=web/pages&page_id=68_68>
DG8SAQ VNWA 3 and 3EC models and packages available.

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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