Ka-band compact filter design on LTCC technology using coupling matrix optimization CAD

This paper presents a collection of five filters in Ka-band using low temperature co-fired ceramic (LTCC) technology. Its purpose is to show an overview of the compacting possibilities with final sizes of complex designs in LTCC. The coupling matrix method is used in order to synthesize the frequency response of the filters, and the designs are carried out doing a systematic characterization of every coupling structure. A coupling matrix optimization CAD is used to extract coupling coefficients and resonant frequencies, making the tuning of the resonators easier. Two filters are designed with single and dual-mode patch resonators. The rest of the designs are cavity filters; one of these combines different coupling structures, using two different layers where the cavities are situated in order to reduce the final size. Finally, an overall comparison of sizes and insertion losses is given.