| Harmonic Suppressed Dual-Band Bandpass Filter with Independently Tunable Center Frequencies and Bandwidths |
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Girdhari Chaudhary1, Yongchae Jeong1, Jongsik Lim2 |
1Department of Electronics and Information Engineering, Chonbuk National University
2Department of Electrical and Communication Engineering, Soonchunhyang University |
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| Abstract |
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This paper presented a novel approach for the design of a tunable dual-band bandpass filter (BPF) with independently tunable passband center frequencies and bandwidths. The newly proposed dual-band filter principally comprised two dual-mode single band filters using common input/output lines. Each single BPF was realized using a varactor-loaded transmission line resonator. To suppress the harmonics over a broad bandwidth, a defected ground structure was used at the input/output feeding lines. From the experimental results, it was found that the proposed filter exhibited the first passband center frequency tunable range from 1.48 to 1.8 GHz with a 3-dB fractional bandwidth (FBW) variation from 5.76% to 8.55%, while the second passband center's frequency tunable range was 2.40 to 2.88 GHz with a 3-dB FBW variation from 8.28% to 12.42%. The measured results of the proposed filters showed a rejection level of 19 dB up to more than 10 times the highest center frequency of the first passband. |
| Key words:
Defected Ground Structure, Harmonic Suppression, Independently Tunable Center Frequency and Bandwidths, Tunable Dual-Band Bandpass Filter, Varactor Diode |
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