There is an increasing demand and a need to make impedance measure- ments using a prober. One example would be making impedance charac- teristic evaluations of a narrow pitch transmission line at high frequency in order to evaluate the design of RF cir- cuits and IC packages. Another example is performing a precise capacitance characterization of dielectric thin film up to the GHz range. In this pro- duct note, a new solution for this type of measurement is described in which the Agilent Technologies 4291B RF impedance/material analyzer and the Cascade Microtech prober are used.