Full-Wave Simulation of Contact-Nonlinearity-Induced Passive Intermodulation Using a Nonlinear Interface Boundary Model

Metal contact generates weak nonlinearity in the contact interface causing passive intermodulation (PIM) for microwave components. In this letter, we proposed a nonlinear interface boundary model to describe the metal contact nonlinearity and utilized the linearity-nonlinearity separation (LNS) finite-difference time-domain (FDTD) method to implement the full-wave PIM simulation. A PIM level of a rectangular waveguide was calculated, which is consistent with the analytical theory and the experimental results. Electromagnetic (EM)-field distribution of the PIM signal was also extracted, which visualizes the PIM signal propagation in the rectangular waveguide.