An UWB Bandpass Filter Based on Single Ring Resonator and Shorted Stubs Loaded Without Coupled Feed Lines

Abstract

This paper presents a very wideband filter intended for the use in ultra wideband (UWB) 3.1–10.6 GHz applications. The UWB bandpass filter (BPF) configuration consists of a single ring resonator (SRR) and four quarter-wavelength shorted circuited stubs loaded on the ring without coupled feed lines. The design was successfully realized in theory and verified by full-wave EM simulation of the full layout and experiment. Because there are no coupled lines, no DGS or CPW structures, this filter is easy to be fabricated with low cost, simple structure, and compact size. Both simulated and measured results show that the filter has a good performance, including ultra wideband from 3.0 GHz to 10.3 GHz with a 106% fractional bandwidth (FBW), low insertion loss (lower than −0.22 dB), and a small group delay variation.