Triple-Mode Bandpass Filter Based on Silver-Loaded Ring-Shaped Dielectric Resonator

In this letter, a triple-mode bandpass filter based on a hollow silver-loaded ring-shaped dielectric resonator (RSDR) is designed by combining a dominant TE
_01δ
mode with a high-order degenerate HE
_11δ
pair. Because of the distinct E-field distribution, the frequencies of the HE
_11δ
pair can be pulled down and split using a loaded silver segment on top of a dielectric. Moreover, the silver segment has a negligible effect on TE
_01δ
and higher order TM
_01δ
modes, implying separation between a passband and adjacent interferers. To validate the methodology, a prototype silver-loaded RSDR is excited by the two L-type feeding probes to satisfy the requirements of coupling strengths for different modes.