Broadband material characterization method using a CPW with a novel calibration technique

When combining contactless power and data transfer, antennas are often placed near magnetic materials with unknown RF properties. While permittivity measurement methods for dielectric materials at RF frequencies are well established, methods for permeability measurement are relatively scarce and often cumbersome. We propose a versatile and easy-to-use method that is applicable to both dielectric and magnetic materials, which uses a coplanar waveguide structure to measure the complex permittivity and permeability in the 1–16 GHz range. We combine the Nicolson–Ross–Weir algorithm with a robust root selection and a conformal mapping method to extract the permittivity and permeability from the measurement data. Moreover, we propose a novel calibration method that uses a single reference dielectric to increase the accuracy of the measured permittivity significantly, even when measuring magnetic materials.