Ultra-wideband bandpass filter with a notch band using multi-mode stub loaded resonator

Abstract

New ultra wideband (UWB) bandpass filter (BPF) with a notch band at 5.8 GHz using multi-mode stub-loaded resonator (SLR) is presented. The very sharp roll-off UWB characteristics of the proposed filter can be easily obtained by using the SLR. The multi-mode stub-loaded resonator consists of two propagation paths with λ/4 open-circuited stubs for providing the two transmission zeros at lower and upper passband edge. The notch band at 5.8 GHz can be well determined by tuning the structural parameters of the asymmetric interdigital coupled input/output (I/O) lines. This study mainly provides a simple method to design the high passband selectivity UWB filter with notch band for Federal Communications Commission(FCC-defined) indoor UWB specification. Experimental verification is provided and good agreement has been found between simulation and measurement.