volume | PIER Journals

Abstract

This paper presents a dual-band tunable bandpass filter with independently controllable dual passbands based on a novel asymmetric λ/4 resonator pair with shared via-hole ground. Because two separated passbands can be independently generated by the two λ/4 resonators with different electric lengths, the asymmetric λ/4 resonator pair can realize flexible passband allocation when it is utilized to design dual-band filters. Two varactors are placed at the two open circuit ends of the asymmetric λ/4 resonator pair to control the two dominant resonant frequencies, respectively. A prototype tunable dual-band filter with Chebyshev response is designed and fabricated. The measured results are in good agreement with the full-wave simulated ones. The results show that the first passband varies in a frequency range from 0.88 GHz to 1.12 GHz with the 3-dB fractional bandwidth of 5.1%-6.4%, while the second passband can be tuned from 1.5 GHz to 1.81 GHz with the 3-dB fractional bandwidth of 5.4%-6.4%.

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Dr. Fei Liang

Dr. Xiaofei Zhai

Dr. Wenzhong Lu

Dr. Qianxing Wan

Dr. Yanyu Zhang