Compact UWB Filter Based on Surface-Coupled Structure with Dual Notched Bands

A novel compact ultra-wideband (UWB) band-pass filter (BPF) based on surface-coupled structure is proposed. The surface-coupled structures and Y-shaped shorted stub resonator are adopted as quasi-lumped circuit elements to achieve UWB pass-band. To avoid the interference of the wireless local area network (WLAN) at 5.25 and 5.775 GHz, two different quarter-wavelength lines are arranged on the ground of UWB BPF to generate dual narrow stop bands. Being developed from the quasi-lumped elements, the proposed UWB BPFs have very compact size. The fabricated UWB BPFs have the advantages of low insertion loss, good selectivity and flat group delay. Good agreement between equivalent circuit modeled, simulated and measured responses of these filters is demonstrated.