TUNING EFFECT ANALYSIS OF CYLINDRICAL DIELECTRIC-LOADED RESONATORS

In this article we analyze the resonant characteristics of cylindrical dielectric-loaded resonators based on a two-dimensional cylindrical f inite-difference-time-domain method (2D-CFDTD). First we validate our approach by comparing the computed data for a specified structure with that available in the literature with the use of other techniques, an d we observe good agreement. Second, we study the tuning effects of tw o resonator configurations: those with a tuning screw and those with a capped tuning screw. In computer experiments, we have found two inter esting phenomena: (i) the length of turning screw can significantly af fect the resonant frequencies Lip to 15% for only a short variation of the screw tuning length, and (ii) the resonant frequencies of TE and TM modes exhibit different tendencies when the screw tuning lengths of structures are changed. Finally, we investigate the field distributio ns inside the resonators by combining the 2D-CFDTD with the discrete F ourier transform, and we have found that the tuning can lead to a larg e alteration of the electromagnetic fields inside the structures. (C) 1997 John Wiley & Sons, Inc.