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Substrate integrated folded waveguide controllable mixed electric and magnetic coupling structure and its application to millimetre‐wave pseudo‐elliptic filters
Author(s) -
Li Xiang,
You Changjiang,
Yu Hongfang,
He Zhaosheng
Publication year - 2017
Publication title -
international journal of rf and microwave computer‐aided engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.335
H-Index - 39
eISSN - 1099-047X
pISSN - 1096-4290
DOI - 10.1002/mmce.21074
Subject(s) - resonator , coupling (piping) , passband , coplanar waveguide , stopband , materials science , coupling coefficient of resonators , inductive coupling , planar , waveguide , optoelectronics , extremely high frequency , electronic circuit , filter (signal processing) , millimeter , band pass filter , physics , microwave , optics , electrical engineering , computer science , engineering , computer graphics (images) , quantum mechanics , metallurgy
A substrate integrated folded waveguide (SIFW) controllable mixed electric and magnetic coupling structure is proposed and investigated, which is suitable for millimeter‐wave pseudo‐elliptic filter applications. The proposed structure is built by a meandered slot‐line (MSL) combined with an inductive via‐hole in a SIFW cavity, which can support two closely‐spaced resonator modes and achieves a mixed coupling. By adjusting the physical sizes of the mixed coupling structure, the electric and magnetic coupling can be separately controlled and a controllable transmission zero (TZ) can be produced below/above the passband. Furthermore, detailed analysis of the SIFW cavity mode spectrum and the mixed coupling characteristics are presented. Finally, direct‐coupled and cross‐coupled fourth‐order pseudo‐elliptic filters are designed, fabricated and measured to verify the proposed mixed coupling structure. The experimental results show that the proposed filters have good performance, such as high frequency selectivity, compact size, wide upper stopband, and easy integration with other planar circuits.