Improved composite right/left handed transmission line metamaterials and its application in bandpass filters

Abstract

The composite right/left-handed (CRLH) transmission line (TL) is presented as a general metamaterials unit possessing both left-handed (LH) and right-handed (RH) natures. An improved unit cell of composite right/left handed transmission line is proposed. The electrical equivalent circuit of the unit is discussed. In addition, the cell has a better selectivity and out-of-band rejection, which is very distinguished from the conventional CRLH TL cell. And the parameters of the cell are discussed specifically. After properly designed the parameters, a compact narrow bandpass filter is generated. It has a transmission zero at the lower stop band, and is found that the filter enables the remarkable size reduction from the conventional CRLH TL filters.