Compact Ultra-Wide Band Bandpass Filter Design Employing Multiple-Mode Resonator and Defected Ground Structure

A compact bandpass filter (BPF) for ultra wideband (UWB) applications is proposed in this paper. The filter is consisting of two symmetrical multiple-mode resonators (MMRs) connected to quarter-wavelength parallel coupled lines in the input and output ports on the top, and a rectangular shaped defected ground structure (DGS) on the bottom of the filter. This filter provides in the passband an insertion loss of 0.2 dB and a return loss greater than 17 dB. Furthermore, the filter occupies an area of 10.42 x 2 mm2. The simulation results are in satisfactory agreement with the measurement ones reported elsewhere. The proposed UWB-BPF presents good performances in terms of insertion loss, return loss, fractional bandwidth and compact size than those reported in the literature.