Comparison between Microstrip-line and Substrate Integrated Waveguide on Package Substrate in 170 GHz and 300 GHz Bands

This paper studies a low loss transmission line structure for 100 GHz to 300 GHz, which is considered as terahertz bands for 6G. Transmission losses of the microstrip-line (MSL) and the substrate integrated waveguide (SIW) are discussed by theoretical calculations. The theoretical calculations predict the loss of the MSL can be lower than that of the SIW at the very high frequency like the terahertz bands. To confirm the prediction, the MSL and the SIW have been designed and fabricated on the package substrate. The measurement results show that the loss of the SIW is lower than that of the MSL at 170 GHz whereas the loss of the SIW is higher than that of the MSL at 300 GHz as predicted by the theoretical analysis.