An Equivalent Circuit Model to Analyze Passive Intermodulation of Loose Contact Coaxial Connectors

Loose contact coaxial connectors are significant sources of passive intermodulation (PIM) in high-power and high-frequency communication systems. In this paper, a circuit model is presented to analyze PIM distortion in loose contact coaxial connectors. First, the loose contact surface model is built to calculate metal-insulator-metal and metal-metal contact resistance; and a method of time-domain reflectometry is used to verify the additional impedance of the loose contact surface. Then, the loose contact current is investigated to drive the equivalent circuit model of loose contact coaxial connectors. Finally, a two-tone experimental verification is conducted to show that the PIM of a loose contact coaxial connector can be analyzed by this model.