Ultra wideband bandpass filter with dual-notched bands using stub-loaded rectangular ring multi-mode resonator

This paper presents a new ultra wideband (UWB) bandpass filter (BPF) with dual-notched bands (at 5.2/5.7 GHz) using the stub-loaded rectangular ring multi-mode resonator (MMR). The proposed resonator consists of the dual embedded open-circuited stubs for introducing the dual notch bands and connected with a stub-loaded rectangular ring structure for controlling the two transmission zeros (at 3/11 GHz) at both sides of the UWB passband edge. This study mainly provides a simple method to design a UWB bandpass filter with high passband selectivity and dual-notched bands for satisfying the Federal Communications Commission (FCC-defined) indoor UWB specification. Experimental verification is provided and good agreement has been found between simulation and measurement.