The Influence of Metal Contact Surface Roughness on Third-Order Passive Intermodulation

This paper takes copper as the research object, aiming to study the influence of waveguide surfaces roughness and the thickness of the metal surface oxide layer on the Passive Intermodulation (PIM) powered. Starting with the change in shrinkage resistance caused by the deformation of the micro-convex body, two-dimensional and three-dimensional fractal geometric rough surface mathematical models through the W-M function are established. Moreover, the influence of fractal dimensions on the rough surface is analyzed. Then through the Metal-Medium-Metal structure formed by the waveguide connection, the equivalent circuit model is established, and the third-order PIM power is calculated. The results show that the PIM becomes more serious as the roughness of the contact surface increases, and the thickness of the oxide layer on the contact surface increases.