Comparisons of Dielectric Characterization by Microstrip and Grounded Coplanr Waveguide Using Resonator Measurements

This paper presents the dielectric characterization of RF printed circuit boards (PCBs), including dielectric constant (DK) and dissipation factor (DF), by microstrip and grounded coplanar waveguide (GCPW) using straight-line resonator measurements, and compares their performances up to millimeter wave regions. The resonant frequencies for different modes are acquired through the measured transmission coefficients, and the effective dielectric constants of the transmission lines (TLs) can be solved. The DK extraction then becomes an inverse problem where the TL propagation constant is calculated based on an initial DK using some empirical formulas with dispersion effects, and the iteration is proceeded until reaching the acceptable error between calculated value and the measured one. The DF can be estimated based on the solved DK with conductor loss including surface roughness. The proposed method is examined by the RO3003 substrate in the frequency range of 18 GHz to 75 GHz.