Reconfigurable Dual-Band Bandpass Filter Using Stub-Loaded Stepped-Impedance Resonators

This paper proposes a reconfigurable dual-band microstrip bandpass filter based on dual-mode stub-loaded stepped-impedance resonators. The proposed structure has a high selectivity with the four transmission zeroes and two control voltages. A source-load coupling technique was employed to enhance the effective control of the passbands. Two identical varactors are loaded at the open ends of each resonator for the purpose of tuning. To verify, the proposed dual-band bandpass filter was designed and simulated. The results show two passbands, with center frequencies of 1.02 GHz and 2.3 GHz, a less than 0.5-dB insertion loss and a rejection of more than 35-dB between the two passbands. The first passband has a tuning range of 1.02 to 1.4Ghz, while the second passband’s frequency can be tuned from 2.0 GHz to 2.6 GHz.

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