新型双模方环微带带通滤波器简

Novel dual-mode square loop microstrip bandpass filter

This paper presents a novel dual-mode square loop resonator with a compact size. Firstly, the odd-even-mode method is utilized to analyze the resonant property of the proposed resonator since its structure is symmetrical, and the passband center frequency can be easily tuned by changing the lengths of a pair of loaded open-ended stubs. Secondly, source-load coupling is introduced to produce a new transmission zero and improve the passband selectivity. Finally, a microstrip dual-mode bandpass filter (BPF) centering at 1.95GHz with a 3dB fractional bandwidth (FBW) of 37.7％ is designed and fabricated. The measured and simulated results in good agreement are presented.