Determination of optimal sample length for passive intermodulation measurements in microstrip lines with non-contact connections

Abstract

In the passive intermodulation (PIM) measurement of microstrip lines using non-contact planar connector, this letter presents a proper sample length for the 3rd-order PIM measurement due to closely frequency-spaced transmission waves. Our experimental study using nickel-plated samples as a distributed PIM source reveals that a spacing between non-contact connectors should be a quarter guided wavelength in order to suppress the effect of non-contact connectors on the PIM measurement results and maximize the observed reverse PIM. We also demonstrate a circuit-network simulation using the harmonic balance method, which agrees well with and validates the experiments.