Dual-Mode Bandpass Filters Using Microstrip Slotted Equilateral Triangular Patch Resonators

Weiliang HU  Zhewang MA  Yoshio KOBAYASHI  Tetsuo ANADA  Gen HAGIWARA  

IEICE TRANSACTIONS on Electronics   Vol.E89-C   No.4   pp.503-508
Publication Date: 2006/04/01
Online ISSN: 1745-1353
DOI: 10.1093/ietele/e89-c.4.503
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Advanced RF Technologies for Compact Wireless Equipment and Mobile Phones)
dual-mode filter,  microstrip filter,  size-reduction,  triangular patch resonator,  

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Two compact and low loss dual-mode filters are proposed by using degenerate modes of slotted triangular microstrip patch resonators. The geometrical size and radiation loss of the triangular patch are reduced simultaneously by loading both horizontal and vertical slots. The resonant frequencies of two degenerate modes can be easily controlled by varying the dimensions and positions of the slots. A two-pole dual-mode filter operating at 3.94 GHz with a fractional bandwidth of 4.3% is designed, fabricated, and measured. The measured results verify well the theoretical predictions.