Reconfigurable-Bandwidth DWB BPF With Fixed Operation Frequency and Controllable Stopband

In this brief, a novel planar topology is presented for the design of reconfigurable-bandwidth dual-wideband bandpass filters with fixed operation frequency and controllable stopband. The proposed design is started from a three-mode passive filtering structure with five transmission zeros, whose second and third passband edges can be independently allocated. Then, two PIN diodes are used as the tuning elements. With the help of these PIN diodes, three bandwidth states can be achieved. In contrast to the previous works with only independently tunable single passband edges, the first and fourth passband edges of the proposed filter can be reconfigurable in same absolute ranges, while the rest two ones are unaltered. For validation, a reconfigurable prototype is designed and measured. The measured results agree well with the theoretical analysis, verifying a simple design approach of DWB BPFs with new reconfigurable-bandwidth property.