Passive intermodulation analysis of single contact junctions of wire mesh

Because the nonlinearity of contact junctions in a wire mesh is the main source of passive intermodulation (PIM) generation, this work aims to analyze the PIM problem of single contact junctions. This work first derives the formulas of micro-contact effects, which reveals the mathematical relationship between the contact force and the micro-contact effects for a single contact junction of a wire mesh. Then, an equivalent circuit model describing contact nonlinearity is constructed to evaluate the nonlinear current through a single contact junction. Finally, an experimental platform is built to test the current through a single contact junction of two metal wires. The PIM power levels of a single contact junction are determined by the finite difference time domain method. The comparison of PIM power levels between the theoretical and experimental results is illustrated to verify the validity of the proposed method. The research results indicate PIM is influenced greatly by the contact forces of junctions. The appropriate contact forces on junctions of wire mesh are beneficial to reduce PIM distortion.