Compact dual-bandstop filter based on composite right/left handed transmission line

This letter presents a novel compact dual-bandstop filter based on composite right/left handed transmission line (CRLH-TL) resonator. By tuning the length of the shunted stubs in the CRLH-TL resonator, each of the two stopbands can be controlled independently. The resonant properties of CRLH-TL resonators are interpreted. A T-shaped microstrip line is applied to improve the passband performance. The equivalent circuit for the presented filter is developed to analyze its performance and detailed design procedures are presented. The simulated and measured results of the final fabricated dual-bandstop filter are found in good agreement with each other. The maximum attenuation is 36 dB in the first stopband and 31 dB in the second stopband with a compact size of 0.21 λg×0.15 λg. Furthermore, a wide passband with low insertion loss is also obtained. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:958–962, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27516

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