COMPACT AND HIGH SELECTIVITY DUAL-BAND DUAL-MODE MICROSTRIP BPF WITH FIVE TRANSMISSION ZEROS

In this letter, a compact and high selectivity dual-band dual-mode microstrip bandpass filter (BPF) with the source-load coupling is proposed using the single short-circuited stub-loaded stepped-impedance resonator. The resonator can generate two resonant modes in each band. The short-circuited stub at the central can only adjust the even mode resonant frequencies, whereas the odd mode ones are fixed. The resonator utilizes the odd and even mode resonators' fundamental resonant frequencies and second harmonic ones to generate the first and second passbands, respectively. Five transmission zeros are created near the passband edges and in the upper-stopband to improve the selectivity. Simulation and measurement results of the dual-band BPF operated at 1.575 and 5.2 GHz demonstrate that the proposed filter is feasible. (C) 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:79-81, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26508