Broadband Ku- and Ka-Band Circulators in LTCC Using Sintered Bulk Ferrites

This paper presents a novel approach of designing and fabricating compact microstrip circulators in low-temperature co-fired ceramics (LTCC) for Ku- and Ka-band satellite communications. State-of-the-art soft ferrites are embedded into LTCC boards as sintered bulk ceramics by using an advanced co-firing technology. The combination of (1) precise machining of the ferrites and low tolerance shrinking and (2) careful EM modelling by taking into account technological constraints, leads to reproducible fabrication and good circulator characteristics. We report simulation and measurement results in good agreement for broadband designs in Ku- and Ka-band.