A new method to measure permittivity and permeability in nanopow der materials in microwave range

摘要

A new method for measuring the electromagnetic properties (permittivity and permeability) of nanopowder materials in a wide microwave region is presented. Unlike previously developed systems, our experimental setup is based on reflection measurements over a short-circuited transmission line combined with the application of a uniform magnetostatic field. When this field is sufficiently high to saturate the material, the effective permeability of the sample equals the permeability of free space, without modifying its electrical properties. Hence, for each frequency, the permittivity can be obtained through the measurement of a single scattering parameter, such as the reflection coefficient. After this first measurement, and once the external field is removed, the reflection coefficient can be used again to obtain the permeability by means of the permittivity value obtained before. As the major advantage, this procedure allows the recording of the experimental data in just one sweep, using one-port measurements, and without modifying the geometrical characteristics of the sample holder. Hence, the measurement process can be easily automated.