Millimeter-Wave Fully Metallic Leaky Wave Antenna With Backfire-to-Forward Beam Scanning, High Scanning Rate, and High Efficiency

In this communication, a fully metallic doubly corrugated parallel-plate waveguide (DCPPW)-based leaky wave antenna (LWA) with backfire-to-forward beam scanning (BTF BS), high scanning rate, and high radiation efficiency is presented. The DCPPW is introduced into the design of LWAs as the slow-wave transmission line (SW-TL), enabling a high scanning rate for its high-dispersion characteristics. The periodic transverse modulation slots are loaded on the upper plate of the SW-TL to stimulate higher spatial harmonics, and, further, generate leaky wave radiation. In order to obtain BTF BS, theoretical conditions are proposed for the dispersion characteristics of DCPPW and modulation period. The grooves under each modulation slot are designed with different depths to suppress the open stopband (OSB) effect. Both ends of the antenna are designed as slopes to correct the beam deflection near the backfire region. A continuous BS from −90° to +11° is obtained within the operating band of 26.5–40 GHz, which indicates a 2.49°/%BW scanning rate. The peak gain varies smoothly from 13.5 to 18.8 dBi with the increase of frequency, and the radiation efficiency is above 90% within the band of 27.1–40 GHz (95.6% of the operating bandwidth). The proposed LWA can perform with the advantages of BTF BS, high scanning rate, and high radiation efficiency, showing a potential to be applied in the millimeter-wave (mmW) imaging and radar systems.