Accurate Characterization of Attenuation Constants of Substrate Integrated Waveguide Using Resonator Method

A novel resonator method is presented to extract the attenuation constants of the substrate integrated waveguide (SIW) transmission lines, providing an alternative way to investigate the propagation properties of SIW. The losses of SIW transmission line and cavity resonator have been investigated with theoretical analysis. Then a formula is derived for establishing the relationship between the attenuation constant of the SIW transmission line and the unloaded Q-factor of SIW cavity resonator at its resonant frequency. Thus, the attenuation constant of SIW transmission line can be extracted using SIW cavity resonator. Good agreement between the resonator method and Thru-Line (TL) method has been achieved in both full-wave simulation and experimental results. Besides, good robustness of the resonator method has been demonstrated, suggesting it is a promising technique for investigation of the propagation properties of SIW.