40/50 GHz diplexer design in LTCC technology

A novel design method of a low-temperature co-fired ceramic (LTCC) diplexer with a substrate integrated waveguide is proposed by taking advantage of the existence of multiple cavity modes. The major design concept is to properly choose the geometric shape of the substrate integrated waveguide resonators to control the resonant frequencies and the position of the feeding probes to achieve the desired isolation between two resonant bands. A 40/50 GHz diplexer design example with two-order response is given and verified by experiments.