Most VNA calibrations are performed referenced to 50 ohms, as this is usually set by the calibration kit. While some calibration kits exist for other impedances (75 ohm N and F connectors for example), they are not common and a custom impedance may be of interest. The impedance transformation function allows performance of a calibration in one impedance and then transformation of the result to appear as if it had been calibrated in a different impedance. As a crude example, if a 75 ohm N calibration kit is not available, but a 50 ohm kit is, neglecting issues with adapters, the 50 ohm calibration could be performed and the utility used to reference the results to 75 ohms. The IMPED. TRANSF. (IMPEDANCE TRANSFORMATION) menu for this function is shown below (Figure: IMPED. TRANSF. (IMPEDANCE TRANSFORMATION) Menu).

The ports can be set independently by using the Port Number toggle button and can be set to any complex value except 0 (zero). Generally, a non-real value will only have meaning in a narrowed frequency range.

A calibration must be active for impedance transformation to take effect and only those ports currently calibrated will be affected.