Negative Permittivity Metamaterial for Microwave Circuit Applications

This paper presents a design for suppressing the second spurious passband associated with meandered parallel coupled-line bandpass filters. Complementary split-ring resonators (CSRRs) are integrated into the filter architecture to provide spurious suppression. This new filter structure maintains its passband performance and deep rejections in the stopband whilst, eliminating the unwanted higher order spurious passband by placing compact CSRRs within the filter active region. In doing so, the compactness of the device is unchanged. Compared with the original structure the proposed design suppresses the spurious at approximately 3f0 where rejection levels reach below -15 dB.