Multilayer Composite Right/Left-Hand Transmission Line with Ultra-Wideband and Miniaturized Characteristics

In this paper, a novel composite right/left-hand (CRLH) transmission line (TL) is proposed and implemented based on the multilayer substrate integrated waveguide (SIW) technology. With the enlarged broadside coupling (series capacitor) via an elliptical slot located in the middle layer, and reversed phase relationship, we successfully extend the bandwidth of the left-handed (LH) passband to 60.5%, and achieve dual right-handed (RH) passbands, with 36.4% and 33.9% bandwidth. Thus, balanced ultra-wideband propagation is obtained. Meanwhile, the cut-off frequency of the waveguide-based structure is reduced to 6.5GHz from the original 10.5 GHz of the SIW TL, resulting in substantial miniaturization.