Novel dielectric resonator structures for future microwave communication systems

Recent progress in manufacturing dielectric ceramics and single crystals with low microwave losses is a challenge for the development of novel devices for microwave communication. Device performance is expected to benefit if novel dielectric resonator structures with low loss contribution of the metallic housing would become available. As a first example of novel devices, high-Q quasielliptic filters with application potential for mobile and satellite communication will be presented. We have achieved unloaded quality factors of 30,000 for C-band quasielliptic filters based on BMT including losses associated with the filter housing. The second example is low-phase noise oscillators and secondary frequency standards based on cryogenic whispering-gallery mode resonators machined from sapphire. We have demonstrated an all-cryogenic K-band feedback oscillator for f=23 GHz with phase noise superior to quartz stabilised oscillators. Finally, first ideas about photonic bandgap resonators based on low loss dielectrics will be presented.