Mitigation of Passive Intermodulation on Planar Microstrip Circuits with Distributed Current-Driven Nonlinearities

This paper presents a simple technique for effective mitigation of passive intermodulation generated in planar microwave circuits fabricated on commercial printed circuit board laminates. The proposed procedure is based on covering the edges of a microstrip lines with a material of a high dielectric constant, which reduces the electric field intensity (displacement field) and, hence, nonlinear distortions due to high current density. The obtained results indicate that proper choice of electrical and geometric parameters of the coating dielectric material result in a significant mitigation of passive intermodulation, while small-signal scattering parameters of the measured circuit remain constant.