A Novel Waveguide to Microstrip Transition in Millimeter-Wave LTCC Module

In this paper, a novel Ka-band rectangular waveguide to microstrip transition in LTCC (low temperature co-fired ceramic) modules is presented. This structure is based on the principle of slot coupling between waveguide and microstrip, and has the metal filled via holes as waveguide walls in LTCC multi-layer substrates. This type of waveguide to microstrip transition eliminates the need for specially shaped LTCC substrate inside the waveguide and is very tolerant to small errors in mechanical misalignment between the LTCC substrate and the rectangular waveguide. This proposed structure is validated by full-wave simulations and experimental measurements.