Sensitivity and resolution of evanescent microwave microscope

A near-field evanescent microwave microscope is based on a /spl lambda//4 coaxial TEM transmission-line resonator with a silver-plated tungsten tip extending through an end-wall aperture. This microwave microscope is used to characterize local electromagnetic properties of dielectrics, conductors, and superconductors. The resolution of the probe is verified experimentally by scanning etched gold lines on a sapphire substrate. A first-order sensitivity estimation generated from a unified equivalent circuit model of the probe and sample is investigated. The sensitivity inherent to the resonant probe and system noise is discussed. Experimental validation of sensitivity is given.