Analysis of 3rd-order passive intermodulation generated from metallic materials

Passive Intermodulation (PIM) is caused by weak nonlinearity in a passive circuit, which has been discussed as interference in high-power microwave base-station systems. While PIM has such a negative aspect, it is applicable positively to finding defected contacts. This paper proposes a modified FDTD method involving current-mode nonlinearity. A technique to reduce the computation time using a linear calculation is also proposed. Although the study is limited to order 3 for a basic examination, validity of the proposed method is confirmed through an experiment using the open-ended coaxial method.