Design of leaky-wave antenna with wide beam-scanning angle and low cross-polarisation using novel miniaturised composite right/left-handed transmission line

In this study, a novel periodic leaky-wave antenna (LWA) with wide beam-scanning angle and low cross-polarisation is proposed by using miniaturised composite right/left-handed transmission line (CRLH TL). By introducing the metallic holes loaded in the interdigital lines of the miniaturised CRLH TL, not only the parasitic resonant modes can be eliminated, but also the miniaturisation is realised. Considering the continuous phase constants from negative to positive values of the balanced CRLH TL, a continuous beam-scanning property from backward to forward of the resultant LWA can be obtained. For verification, a periodic LWA, which consists of 20 unit cells of the balanced CRLH TL, is fabricated and measured; the measured and simulated results are in good agreements with each other, indicating that the fabricated LWA operates from 3.90 to 4.90 GHz (a bandwidth of 22.7%), and has a wide continuous beam-scanning capability from backward −61° to forward 67° (including the broadside) within the operating band. Moreover, it also has very low cross-polarisation, which remains at a level of at least 25 dB below the co-polarisation across the entire radiation region. As a result, the presented LWA should find promising applications in modern wireless communication systems and the high-resolution radar system due to these wonderful electromagnetic performances.