[TowerTalk] Measuring Common Mode Choke with Anritsu VNA

Steve Hunt steve at karinya.net
Sun Dec 31 04:39:49 EST 2017


I don't think that instrument will allow you to see the Zcm of a choke 
directly on-screen.

However, it looks like it will display |S21| directly. With the choke 
connected between the two ports, |S21| will give you a good indication 
of |Zcm| for the high values we are mostly interested in [e.g. 
|S21|=-40dB implies |Zcm|=10,000Ohms]. The |S21| scan will also allow 
you to quickly see the resonant frequency of the choke.

What you wont see easily is the Q of the choke, unless the instrument 
can also display the phase of S21.

Steve G3TXQ

On 30/12/2017 20:41, Máximo EA1DDO_HK1H wrote:
> What I can do, and in fact I do, is to export the measure in .s2p Touchstone format, then apply some maths on a excel sheet to convert LogMag and Phase to complex R, complex I, and finally complex Z. All of that on Excel.
> But to get that directly on screen would be much better.

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