Compact Dual-Band Bandpass Filter Based on SSL-SIR With Sharp Roll-Off

Abstract

A compact dual-band bandpass filter (DB-BPF) is studied and implemented by using shorted stub-loaded stepped impedance resonator (SSL-SIR) and 0◦ feed structure in this paper. The resonance frequencies of SSL-SIR can be analyzed and explained by odd-even mode analysis method and it is used in the design of BPF I. Then, the BPF II is created using the theory of 0◦feed structure. Finally, the two structures are combined together to form a DB-BPF by reasonably adjusting the coupling between them and the position of the feed points. The simulation results suggest that the center frequencies of the two passbands are 3.45 and 5.2 GHz, respectively, which are suitable for modern wireless communication systems like 5G and WLAN. Compact size, strong passband isolation, and large stopband bandwidth are all advantages of the proposed DB-BPF filter. A prototype is created and constructed to validate this. The simulated results are in good agreement with the measured results.