An SIW Based Leaky-Wave Antenna with Wide Beam Scanning and Low Cross-Polarization

In this letter, a substrate-integrated waveguide (SIW) based leaky-wave antenna (LWA) with wide beam scanning and low cross-polarization is investigated. Firstly, a 15-unit cell LWA is realized through etching periodic symmetrical grid slots (SGS) on the surface of a single-layer SIW. Then, to reduce the open-stop band (OSB) effect and improve impedance matching, multiple rows of zigzag-shaped posts (ZSP) are loaded on both sides of the SGS. An equivalent circuit model is derived to theoretically investigate the properties of the unit cell. Due to the symmetrical structure relative to the longitudinal centerline of the SIW, a low level of cross-polarization is attained throughout the band. Finally, a prototype of the proposed LWA is manufactured and measured. The measured -11 dB impedance bandwidth spans from 24.0 to 40.5 GHz, offering a wide continuous beam scanning range of 98° from -39° to 59°. The cross-polarization level is lower than -39 dB over the whole bandwidth, and the peak gain is 15 dBi. The performance of the proposed LWA makes it a competitive candidate for applications in mmWave systems.