Dual-mode half-cut dielectric resonator filters

This paper shows that it is feasible to realize a quadruple-mode dielectric resonator. A half-cut of this resonator is then shown to support two modes. A new type of dual-mode dielectric resonator filters is introduced, using a cylindrical resonator cut in half along its axis. Center frequency control, intra/inter/input-coupling mechanisms, tuning, and spurious improvement methods are discussed, showing versatility of the proposed structure. Practical filter measurement results are presented which verify the proposed concept. The filter provides improvements in terms of size and mass reduction, in comparison with existing dual-mode dielectric resonator filters, while maintaining better spurious performance, with a small degradation in quality factor. It is a low-cost compact solution, suitable for both wireless and satellite applications.

I. Introduction

Dielectric Resonators (DR) are traditionally employed as single-mode resonators [1]–[3], dual-mode resonators [2]–[5] or triple-mode resonators [6]. There has been limited interest to investigate the possibility of realizing quadruple-mode dielectric resonators [7], mainly because quadruple-mode filters are not easy to tune. The coupling and tuning mechanisms must permit an independent control of the four operating modes. In practice however, having many screws in one cavity increases complexity. This problem is more pronounced in quadruple mode filters but also exists in triple-mode and traditional dual-mode DR filters.