Modelling the pin gap effect in coaxial connectors

A model using equivalent shunt susceptance is proposed to characterise the pin gap effect in pin and socket type coaxial connectors. An empirical formula for the susceptance as a function of the gap parameters has been deduced using numerical simulation for five different metrology grade precision connectors. The simplicity of the pin gap model permits easy embedment in Vector Network Analyser (VNA) measurement modelling. The reflection coefficient due to pin gaps in a beadless air line has been calculated using the model and compared with measurement results. The comparison indicates significant contribution of the pin gap effect to VNA measurement uncertainty.