An LTCC-based 35-GHz substrate-integrated-waveguide bandpass filter

Low-temperature co-fired ceramic (LTCC) is used for a novel bandpass filter implementation. The filter is based on a substrate-integrated waveguide (SIW) having its pass band around 35 GHz. The implementation of this filter illustrates the feasibility of LTCC at these frequencies. Using a microstrip-to-SIW transition for coupling the first resonator additionally reduces the filter´s size and loss. The filter is designed such that active components (e.g. MMIC amplifiers) can be placed into a cavity right next to the filter. Filter syntheses has been done by extracting the length of the resonators and the insertion loss of the irises. This method reduces optimization time significantly.