Influence of RF Probe Tip Geometry on Surface Wave Generation in Millimeter-Wave on-Wafer Characterization

This paper investigates the influence of probe tip geometry on the excitation of surface waves and radiated power in high-frequency on-wafer measurements, focusing on two commercially available RF probes with planar and microstrip tip structures. The study is conducted across the DC-110 GHz frequency band and employs two distinct approaches: the first studies surface wave generation at the contact point between the probe and the substrate, while the second examines the surface wave power. For both approaches, simulation and measurement results are presented and aligned with each other, showing that the probe with planar tip configuration contributes more to the generation of surface waves and radiation into the air, compared with the microstrip tip probe.