A 79-GHz LTCC differential microstrip line to laminated waveguide transition using high permittivity material

A differential microstrip line (DMSL) to laminated waveguide (LWG) transition based on low temperature co-fired ceramic technology is presented in this paper. The transition is designed for the 76 - 81 GHz radar frequency band using high permittivity material (ε_r = 7.4). The achieved bandwidth at 10 dB return loss is more than 10 GHz. For measurement purposes, another metallic rectangular waveguide to LWG transition was designed and cascaded with the DMSL-to-LWG transition. The measurement results of the fabricated prototype agree closely with the simulation. The designed transition simplifies the application of monolithic microwave integrated circuits with differential outputs and enables low-cost integration of W-band radar components on ceramic substrate.