Determination of the complex permittivity of each layer for a bi-layer dielectric material using transmission (ABCD) matrix in Ku-Band frequency

Abstract

A new technique is presented to determine the complex permittivity of each layer for a bi-layer dielectric material. The bilayer material sample is loaded in a Ku-band rectangular waveguide WR62 and its two port S-parameters are measured as a function of frequency using the E8634A Network Analyzer. Also, by applying transmission (ABCD) matrix, expressions for the S-parameters of the bi-layer dielectric material as a function of complex permittivity of each layer are developed. To estimate the complex permittivity of each layer’s dielectric material, the square sums of errors between the measured and calculated S-parameters are minimised using a nonlinear optimization algorithm. The complex permittivity of each layer for a bi-layer dielectric material such as FR4-Teflon, FR4-Delrin and Delrin-Teflon are determined at the Ku-band frequencies, and the average relative errors between the individual dielectric materials and those of each individual layer of the bi-layer dielectric materials are calculated.