Abstract
This paper presents new compact microstrip bandpass filters with bandwidth control by employing DGS resonators. The proposed bandpass filters consists of two coupled DGS resonators with a microstrip excitation. The bandwidth can be controlled by choosing the coupling structure between the two DGS resonators. The wider bandwidth can be achieved by adding a strip conductor between the two DGS resonators. However, the narrow bandwidth can be obtained by etching a slot in the strip conductor placed between the DGS resonators. The widths of the strip conductor and the etched slot control the filter bandwidth. Fractional bandwidth (FBW) from about 2.5% or less to more than 22% can be achieved by this design approach. The concept has been validated through the design and implementation of two filters with FBW of 6% and 12.9%. Measurements agree well with theoretical results.