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A compact wide stopband bandpass filter, based on composite right/left handed transmission line (CRLH-TL), is proposed in this article. The prototype filter has a wide stopband performance, a compact size and low insertion loss in the passband. A backside aperture is applied below the inter-digital part to realize a strong coupling between the fingers. The filter achieves a sharp stopband at both sides of the passband and low insertion loss within the passband. The properties of CRLH-TL enable the spurious responses to emerge far away from the passband of the bandpass filter. To further improve its upper stopband, two U-shaped defected ground structures (DGS) are placed at the input and output feed lines, respectively. Both filters are designed, simulated and fabricated. The measured results show good agreement with the simulated ones. [ABSTRACT FROM AUTHOR]