Miniature Triple-Mode Dielectric Resonator Filters

• Published in: IEEE transactions on microwave theory and techniques Vol. 66; no. 12; pp. 5625 - 5631
• Main Authors: Bakr, Mustafa S., Hunter, Ian C., Bosch, Wolfgang
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.12.2018; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Bandpass filters; Cavity resonators; Couplings; Dielectrics; Filtering theory; Filters; Finite element method; finite transmission zeros; Microwave filters; Microwave theory and techniques; miniaturization; Probes; Resonant frequency; Resonators; triple-mode; triplets
• ISSN: 0018-9480; 1557-9670
• DOI: 10.1109/TMTT.2018.2873309

In this paper, a new class of triple-mode microwave filters is presented. These devices use the degenerate pair of the <inline-formula> <tex-math notation="LaTeX">HE_{11\delta } </tex-math></inline-formula> mode and the single <inline-formula> <tex-math notation="LaTeX">TM_{01\delta } </tex-math></inline-formula> mode in dielectric-loaded cavities with an unloaded <inline-formula> <tex-math notation="LaTeX">Q </tex-math></inline-formula>-factor of 3000-5000 and reasonable spurious-free window. The proposed structure is obtainable in less than one-quarter of the physical volume of equivalent TEM filters. A finite-element method solver for electromagnetic structures (HFSS) is used to study the main properties of this resonator. Fundamental design rules for triple-mode bandpass filters with controllable finite transmission zeros are presented. Design examples of bandpass filters with finite transmission zeros on the high or low or both sides of the passband are demonstrated. Measured results demonstrate excellent performance.