Compact single layer travelling-wave antenna design using metamaterial transmission lines

This paper presents a single-layer travelling-wave antenna (TWA) that is based on composite right/left-handed (CRLH)-metamaterial (MTM) transmission-line (TL) structure, which is implemented by using a combination of inter-digital capacitors and dual-spiral inductive slots. By embedding dual-spiral inductive slots inside the CRLH MTM-TL results in a compact TWA. Dimensions of the proposed CRLH MTM-TL TWA is 21.5×30.0 mm2 or 0.372λ0×0.520λ0 at 5.2 GHz (center frequency). The fabricated TWA operates over 1.8–8.6 GHz with a fractional bandwidth greater than 120%, and it exhibits a peak gain and radiation efficiency of 4.2 dBi and 81%, respectively, at 5 GHz. By avoiding the use of lumped components, via-holes or defected ground structures (DGS), the proposed TWA design is economic for mass production as well as easy to integrate with wireless communication systems