Matching network design for passive intermodulation distortion reduction

A method for designing matching networks to reduce the distortion created by nonlinear passive components interfacing with antennas is presented. Coaxial connectors produce passive intermodulation distortion based on the amount of current flowing through them. By increasing the input impedance at the connector using impedance transformations, current, and thereby passive intermodulation distortion, can be reduced. A model is developed which allows designers to understand the relationship between impedance and distortion. Experimentally a reduction greater than 20 dB in passive intermodulation distortion is shown using a λ/4 matching network to transform the input impedance at the passive intermodulation source from 50Ω to 285Ω, while minimally affecting the linear transmission properties of the connection.