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.


Electrical and Computer Engineering

Research Center/Lab(s)

Electromagnetic Compatibility (EMC) Laboratory


National Natural Science Foundation (China)
Science and Technology Major Project of Hunan Province


This work was supported in part by the National Natural Science Foundation of China under Grant 61771190 and Grant 61671203, and in part by the Science and Technology Major Project of Hunan Province under Grant 2017GK1051.

Keywords and Phrases

Circuit simulation; Connectors (structural); Contacts (fluid mechanics); Electric resistance; Intermodulation distortion; Intermodulation measurement; Metals; Surface resistance; Time domain analysis; Timing circuits; Transmission line theory; Coaxial connectors; Integrated circuit modeling; Metal contacts; Passive intermodulation (PIM); Surface impedances; Equivalent circuits; Loose contact; Metal-insulator-metal contact (MIM); Metal-metal contact (MM)

International Standard Serial Number (ISSN)

0018-9375; 1558-187X

Document Type

Article - Journal

Document Version


File Type





© 2018 Institute of Electrical and Electronics Engineers (IEEE), All rights reserved.

Publication Date

01 Oct 2018