Design Of UWB Filter Based On Mutiple Mode Resonator

Ultra-wideband (UWB) wireless technology has been receiving a great amount ofattention due to its high data rate, low transmission energy consumed, flexibility andmobility since the Federal Communications Commission (FCC)’s release in February2002. As one of the essential modules in UWB communication system, UWB filter playa significant role in deciding the overall performance of systems. The UWB bandpassfilter with low cost, compact size and high performance is presented in this paper basedon a stepped-impedance ring resonator, which is constructed by loading twoquarter-wavelength resonators in stepped impedance one-wavelength ring resonator.The UWB indoor limit covers some frequency bands used by existing radiocommunication systems. As some notching bands are desired in the design of UWBbandpass filters， compact UWB bandpass filter with dual-notched bands andtriple-notched bands are elaborate over using dual-mode and triple-mode stub loadedresonator. The main work of this paper can be summarized as follows:1. The novel stepped-impedance ring resonator is proposed. Transmission zerosand resonant characteristics of designed stepped-impedance ring resonator are analyzedin detail via transmission line theory and Even-Odd mode network analysis theory. Thefour transmission poles are relatively uniformly located in UWB pass band, and twotransmission zeros are produced in the lower and upper cutoff edges of desired passband. As the mechanism of the proposed filter is described, UWB bandpass filter has anexcellent in-band performance, high return loss and low insertion loss, as well assharpened rejection skirts may be reached.2. The novel dual-mode folded stub-loaded resonator is proposed. The properties ofthe dual-mode resonator are analyzed at great length via Even-Odd mode networkanalysis theory. The triple notched bands can be achieved at desired frequencies byappropriately adjusting the resonator dimensions. The basic UWB BPF is made up offour folded shunt quarter-wavelength short-circuited stubs separated by connecting lineswith half-wavelength. The coupled folded stub loaded resonator is employed tointroduce the dual notched bands. Good insertion/return losses are achieved through demonstrated in both simulation and experiment.3. The novel triple-mode folded stub-loaded resonator is proposed. Resonantcharacteristics of the raised triple-mode resonator are analyzed by Even-Odd analysistheory. The basic UWB BPF is comprised of optimum folded Short-Circuited Stub Filter.The notch frequencies can be tuned by changing the impedance ratio of the embeddedtriple-mode stub-loaded resonator. The fabricated UWB filter is developed and thein-band and out-of-band performance is obtained by measurement.