Compact fully‐canonical dual‐band bandpass filter with independently controllable bandwidths

Abstract

Abstract A compact four‐order fully‐canonical dual‐band bandpass filter (DBBPF) with independently controllable bandwidths is reported in this letter. The filter comprises of a pair of identical electrically end‐coupled dual‐mode open stub‐loaded resonators (OSLRs) and two different pairs of magnetically coupled λ/4 short‐circuit resonators (SCRs) that are embedded within the OSLRs for compactness. Specifically, the fundamental odd‐ and even‐mode of the OSLRs are coupled with the upper and lower pairs of λ/4 SCRs to generate the first and second passbands, respectively. In addition, the input and output ports feed the two OSLRs and provide a magnetic source‐load coupling for the filter. Owing to the special layout arrangement, the proposed filter can achieve compact size and fully‐canonical frequency response with independently controllable bandwidths, simultaneously. A four‐pole DBBPF protype centred at 2 and 3.5 GHz is designed and implemented. The measurements and the simulated ones are in good consistency.

Keywords

• Passive filters and other passive networks
• Waveguide and microwave transmission line components