Calibrated wideband high frequency passive impedance probe

Abstract

A calibrated passive impedance probe has a wide bandwidth operating range for impedance and performance measurements of RF and microwave components, devices, and circuits in 50Ω and 75Ω environments. The probe is calibrated at the probe tip, thus allowing accurate impedance and performance measurements of in-circuit functions and on-board components. The calibrated probe can be used to eliminate RF connectors and provide input and output connections to a circuit board for prototype design and quick performance verification thus realizing cost savings on RF connectors. The probe includes a semi-rigid coaxial cable assembly filled with dielectric material, a silver plated center conductor, and silver plated ground outer conductor having an SMA male connector on one end and exposed center conductor at the opposite end and having uniform characteristic impedance of 50Ω or 75Ω along the cable length; a hexagonal shaped body made of anodized aluminum having raised texture on the surface for sure handling; a probe tip of gold plated aluminum with two spring loaded ground pins; a four-finger threaded cable catch for locking semi-rigid coaxial cable assembly inside the tip and for ground continuity from cable to spring loaded pins; an interface RF connector-adapter including SMA female-SMA female, BNC-SMA female, or Type N-SMA female; a locking nut to hold and lock cable assembly and connector-adapter inside the probe body; and 50Ω and 75Ω precision loads for probe calibration.