Ku-Band Microstrip Junction Circulators Manufactured using Low Temperature Co-fired Ceramics Technology

The high cost and size of circulators have always been the main drawbacks of these components. Low temperature co-fired ceramics technology (LTCC) could reduce the cost by simplifying the manufacturing process. Two new ferrites with low sintering temperature were developed and evaluated: a garnet-based ferrite with a high permittivity and a spinel-based ferrite with a high saturation magnetization. Two circulators based on these ferrites have been designed using coupled magnetostatic and electromagnetic simulations and fabricated. Their insertion losses and sizes are very close. The high magnetization of the spinel ferrite allows a bandwidth twice as high as the garnet-based circulator. Both circulators showed good performance and demonstrate that low temperature co-fired ceramics technology can be used for the collective realization of low cost circulators.