Novel dielectric resonator structures for future microwave communication systems

Recent progress in manufacturing dielectric ceramics and single crystals wi th 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 met allic housing would become available. As a first example of novel devices, high-Q quasielliptic filters with application potential for mobile and sate llite communication will be presented. We have achieved unloaded quality fa ctors of 30,000 for C-band quasielliptic filters based on BMT including los ses associated with the filter housing. The second example is low-phase noi se oscillators and secondary frequency standards based on cryogenic whisper ing-gallery mode resonators machined from sapphire. We have demonstrated an all-cryogenic K-band feedback oscillator for f= 23 GHz with phase noise su perior to quartz stabilised oscillators. Finally, first ideas about photoni c bandgap resonators based on low loss dielectrics will be presented. (C) 2 001 Elsevier Science Ltd. All rights reserved.