Measurement and calculation of passive intermodulation nonlinear coefficient

Volt-ampere nonlinearity is the origin of passive intermodulation, which means electric field-magnetic field nonlinear behavior of device or structure. Although DC nonlinear measurement is easier, it is not applicable to microwave frequency bands. This paper proposes a method to calculate the non-linear parameters of passive intermodulation—a non-linear parameter calculation method based on multi-state measurement. It is a universal method to measure nonlinear characteristic parameters of passive intermodulation. Then, we measure and calculate the non-linear parameters of passive intermodulation by the undetermined coefficients method and derive the third-order passive intermodulation expression.