High-Frequency Characterization and Modeling of Coaxial Connectors With Degraded Contact Surfaces

Coaxial connectors provide a means to connect and disconnect transmission lines, components, and systems at high signal frequencies. Connector contact degradation has a significant effect on signal transmissions. This paper considers experimental measurements, simulations, and analyses of the high-frequency behaviors of degraded coaxial connector. An experimental investigation was first performed to evaluate how degraded contact surfaces affect the return loss and insertion loss of connectors. It was found that both the input return loss and the insertion loss are frequency-dependent. As the contact surface degrades, the return loss decreases and the insertion loss increases at lower frequencies, with the effect of the degradation becoming smaller with increasing frequency. A 3-D field simulation was developed to evaluate the high-frequency performance of various contact cases. Based on the simulation results, the electrical parameters of the dielectric film were extracted for connectors with different degradation levels. According to the transmission line theory and the contact physics, a high-frequency equivalent model of the degraded coaxial connector was developed and analyzed. This model is helpful in developing a better understanding of possible failure modes and in identifying failure features in fault diagnosis.