Traveling-wave antenna based on metamaterial transmission line structure for use in multiple wireless communication applications

This paper introduces a left-handed metamaterial traveling-wave antenna (TWA) based on metamaterial transmission-line structure to enhance the gain and radiation efficiency of the antenna without trading on its fractional bandwidth. The antenna consists of a series of coupled unit-cells comprising “X-shaped” slots which are inductively terminated to ground. Effective aperture of the antenna can be increased by increasing the number of unit-cells. The consequence of this is enhanced gain and radiation efficiency performance with no adverse affect on its fractional bandwidth. The antenna's characterizing parameters were extracted using 3D electromagnetic simulation tool (HFSS™), and the antenna was fabricated using standard PCB manufacturing techniques on a 1.6 mm thick dielectric substrate with permittivity of 2.2. The antenna operates from 0.4 GHz to 4.7 GHz. The antenna has an electrical size of 0.017λ₀ × 0.006λ₀ × 0.002λ₀, where λ₀ is free space wavelength at 400 MHz. The proposed antenna is significantly smaller than its conventional counterparts. Antenna's measured optimum gain and radiation efficiency are 2 dBi and 65%, respectively, at 2.5 GHz. These features make the antenna attractive for use in multiple wireless communication applications.