A Study on Improvement of the Accuracy in the Ellipsometry Method for Complex Permittivities of Materials in Millimeter-Wave Region

Abstract

The ellipsometry method is well known as one of methods to measure a refractive index in optical region. This method is extended to a measurement for complex permittivities of materials at a millimeter-wave frequency. This method has little limitation on a sample size because of the free space method. The uncertainty on the measurement of phases in reflection doesn’t occur because this method is based on a scalar measurement. But a large uncertainty due to a free-space method was realized. Only 2nd order Fourier coefficients are obtained in an ideal case. But measured data contained higher order coefficients up to the 6^th, because all reflected electromagnetic power could not be received by a horn antenna. We propose an effective method to extract Fourier coefficients only corresponding to ellipsometry parameters. Complex permittivitie of a lossy material in millimeter-wave region can be measured in high accuracy by the improved ellipsometry method.