A planar microstrip implementation of dual-composite right/left handed transmission line

In this paper, a planar microstrip dual-composite right/left-handed transmission line (D-CRLH TL) is proposed. It only includes interdigital capacitor and simple strip elements, which can be easily designed and applied to microwave devices and systems. An effective model is also presented to show its characteristics. This model is more exact than the ideal one. The balanced condition is valid in this D-CRLH model for broadband matching. It exhibits tri-band: the lower right-handed (RH) band, the middle left-handed (LH) band and the higher RH band, which is much different from ideal D-CRLH. Three unit cells of D-CRLH TL are simulated by CST MWS. The whole structure exhibits a DC to 3.4 GHz RH band, a 5.4 GHz to 7.5 GHz LH band and 7 GHz to 10 GHz RH band. The reflectance in pass-band is less than −10dB.