A Simple and Planar Notched-Wideband Bandpass Filter with Multipole Poles and Zeros

A simple and planer quarter-wavelength topology is presented in this paper for the design of notched-wideband bandpass filters (NWB BPFs) with multipole poles and zeros. The proposed design is started from a pair of T-shaped resonators, which owns three poles and four zeros. Then, a pair of parallel coupled-lines (PCLs) are introduced. With the aid of the added parts, extra four poles and two zeros can be introduced. As such, a NWB BPF with seven poles and six zeros can be realized. To validate this, a prototype is designed and measured. As the measured results are in good agreement with the simulated one, a simple and effective design of NWB BPFs can be verified.