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This paper presents a new multi-band stopband filter loaded by a shorted metamaterial circuit. Firstly, two filters loaded by stubs and open ring resonators (ORRs) are studied and compared. The ORRs allow more effects in terms of miniaturization by a shifting toward low frequencies and rejection bandwidth (57.34%). To improve the filter efficiency, coupled split ring resonators (SRRs) are used. The final filter is characterized by a miniaturized size of 18.8x40mm², wide rejection bandwidth, high selectivity level, and multiple resonances over S, C, X, and Ku bands. L-C equivalent circuit model filter and other characteristics are investigated. A prototype of the filter with coupled SRRs has been fabricated and measured. Good matching among EM-simulation, equivalent circuit modelling, and measured results are achieved. [ABSTRACT FROM AUTHOR]

This paper presents the design of UWB threepole modified parallel coupled line bandpass filter with improved rejection in the out-of-band frequencies. To achieve the desired UWB requirements using the conventional bandpass filter design, a physical dimension optimization of space-gap between lines, line widths and lengths was applied. An equivalent circuit model is also presented and demonstrates reasonable agreement with simulation results. The optimized filter demonstrates an excellent UWB performance, covering the Federal Communication Commission spectrum bandwidth with low insertion loss and acceptable selectivity. However, this resulting filter structure presents very small gapping between adjacent resonators; that means the filter is unmanufactured. Then an example of an alternative filter structure is finally proposed with null gaping and shortcircuited stubs that yields to a fabricated prototype with selectivity improvement. Generally speaking, reasonable agreement is achieved between measurement and simulation results. [ABSTRACT FROM AUTHOR]