Designs of Filter Based on Metamaterial Transmission Line

The filter can equalize the amplitudes and phase characteristics of the frequency band in use, and effectively suppress out-of-band noise. Based on the theory of metamaterial transmission line, four types of circuit models for low-pass, high-pass, band-pass and band-reject filters are designed at low-frequency band in ADS software. The results show that the filters with flexible characteristics can be obtained by adjusting the circuit layouts and the values of lumped elements. Compared with conventional filters, metamaterial filters possess many superior performances, such as simpler structure, higher rectangular coefficient and lower group delay etc. Further-more, an experiment of the metamaterial notch filter was carried out to verify the correctness of the proposed metamaterial filters. The design approach of the metamaterial filter circuit not only extends the application range of the transmission line from the microwave frequency to the low frequency band, but also provides an alternative method for filter design.