skrf.calibration.calibration.unterminate(ntwk, gamma_f, gamma_r)[source]

Unterminate switch terms from a raw measurement.

In order to use the 8-term error model on a VNA which employs a switched source, the effects of the switch must be accounted for. This is done through switch terms as described in 1 . The two switch terms are defined as,

\[\Gamma_f = \frac{a2}{b2} ,\qquad\text{sourced by port 1}\ \Gamma_r = \frac{a1}{b1} ,\qquad\text{sourced by port 2}\]

These can be measured by four-sampler VNA’s by setting up user-defined traces onboard the VNA. If the VNA doesnt have 4-samplers, then you can measure switch terms indirectly by using a two-tier two-port calibration. First do a SOLT, then convert the 12-term error coefs to 8-term, and pull out the switch terms.

  • two_port (2-port Network) – the raw measurement

  • gamma_f (1-port Network) – the measured forward switch term. gamma_f = a2/b2 sourced by port1

  • gamma_r (1-port Network) – the measured reverse switch term gamma_r = a1/b1 sourced by port2



Return type

Network object



“Formulations of the Basic Vector Network Analyzer Error Model including Switch Terms” by Roger B. Marks