Design of dual-band bandpass filter with constant absolute bandwidth

A dual-band bandpass filter using split-ring resonators (SRRs) and defected ground structure (DGS) with constant absolute bandwidth is proposed in this article. The inner and outer SRRs are operated for respective passband. DGS is etched on the ground, which can control the coupling coefficient of the filter to maintain constant absolute bandwidth. Finally, such kind of filter with compact size and high selectivity characteristics are designed and fabricated. The simulation and measurement results are basically in good agreement. ? 2014 Wiley Periodicals, Inc.