NEW DUAL-BAND BANDPASS FILTER DESIGN BASED ON SLOTTED GROUND STRUCTURES

Two dual-band bandpass filters featuring flexible frequency choice and compact size are proposed using two kinds of resonators. One is based on two pairs of different dimensional slotted ground resonators; another is based on a pair of slotted ground resonators and a microstrip-stepped impedance resonator. Unlike traditional filters, the harmonics of slotted ground resonators forming the lower passband are tuned to higher frequencies; the resonators forming the lower and upper passband lie at the two sides of signal line, the two passbands can be adjusted to the desired values with expected bandwidth by changing the sizes of the resonators independently. The interactions between them are minor. The proposed filters do not need extra impedance matching network unlike traditional dual-band filters and with the ground plane efficiently used, they are more compact in structure. Both filters are optimized with jumping genes evolutionary algorithms for multiobjectives, such as low-insertion loss, suitable bandwidth, and good stopbands. Two optimized bandpass filters were also implemented. Simulation and measurement results are performed to verify their good characteristics. (C) 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53: 1505-1511, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26028