Compact UWB Bandpass Filter With Dual Notched Bands Using Defected Ground Structures

This letter proposes a novel ultra-wideband (UWB) bandpass filter (BPF) with dual notched bands using triangular defected ground structures (DGS). Two symmetrical dumbbell-shaped interdigital capacitors are formed to improve the BPF's performance. Three pairs of tapered defected ground structures are studied and adopted to suppress the spurious passband by assigning their transmission zeros towards the out of band signal. A small UWB BPF is obtained by combining these two structures. One of the arms in coupled-line sections is extended and folded to create a notched band at 5.3 GHz, and a meander line slot is developed to create another notched band at 7.8 GHz. Simulated and measured results are in good agreement indicating that the proposed BPF has a passband from 2.8 to 11.0 GHz and a wide stopband bandwidth with 20 dB attenuation up to 30.0 GHz.