Estimation of Relative Permittivity of Printed Circuit Board with Fiber Glass Epoxy as Dielectric for UHF Applications

Abstract

This paper presents the results of measuring relative permittivity of fiber glass printed circuit board (PCB’s), using a rectangular resonant cavity. The relative permittivity is presented as function of frequency. To obtain resonant frequencies, the return loss was measured using a network analyzer. Relative permittivity was calculated by finding frequencies of resonant cavity modes. The results are presented in a frequency span of 1 to 3.5GHz. It was clearly shown the nonlinear behavior of the relative permittivity for the dielectric laminate evaluated, even what happens respect to the frequency of the resonant modes below and above to frequency of 2 GHz.