Frequency domain propagation and permittivity characterization method for printed circuit boards

A frequency domain procedure was explored to recover permittivities of printed circuit board (PCB) materials for high-speed and wideband applications. The propagation constant of buried stripline was first extracted from the measured scattering parameters of two test lines with different lengths. The accuracy of the recovered propagation constant was shown to be comparable with that of the time-domain short pulse propagation (SPP) method. The conventional empirical formulas were used to estimate conductor dissipation that was then subtracted from the measured total loss to recover the true permittivity of the PCB material. The experimental results indicate that more sophisticated empirical formulas are needed to accurately recover wideband loss tangent.