The Impact of Coating Materials in Coaxial Connectors on Passive Intermodulation

Passive intermodulation (PIM) induced by coaxial connectors negatively impacts communication quality. The properties of the coating materials alter PIM performance. Accordingly, a better understanding of the influence of the coating materials for coaxial connectors on PIM is of substantial value. In the present work, the effects of coating materials on the PIM performance was investigated through experimental testing, simulation modeling, and analysis. A series of experimental tests were performed to evaluate the third-order intermodulation (IM3) power of selected connector samples with different coatings using a Passive Intermodulation Analyzer. Finite Element Analysis (FEA) simulations were conducted to quantitatively describe the effect of signal frequency, coating thickness, and material properties on the distribution of current density. Based on the results from simulations and the experimental testing, a behavior model describing the relationship of current density and PIM products power was developed and the model parameters for test samples were identified. This model provides an analysis tool for coaxial connector selection and low PIM connector design.