Extraction of dielectric constant based on S-parameter inversion method

In this paper, a new extraction method for the dielectric constant of PCB material is proposed, which is based on S-parameter inversion method. The calculation process is detailed and an application example is given. According to the simulated S-parameters, while with the proposed method, the applicable frequency ranges of a set of published expressions for microstrip lines are obtained. With the calculated results, the accuracy of dielectric constants, which are obtained from the published expressions, is analyzed. The work is helpful to provide reference to calculate the characteristic impedance by using suitable expressions at different frequency.