Simultaneously Enhancing Radiation and Aperture Efficiencies of Leaky Wave Antennas Using Discrete Metasurfaces

Traditional leaky wave antennas (LWAs) designed with remaining power absorbed at the end of the waveguide leads either to poor radiation efficiency or to poor aperture efficiency. In this work, we propose a novel class of LWAs based on discrete metasurfaces. A reflector is placed at the waveguide end to reflect and reuse the remaining power. A novel discrete metasurface is designed to radiate the power leaked from the forward and backward-travelling waves to the same direction. The antenna termination is tuned to realize a constructive interference between the waves leaked from the forward and backward-travelling waves. Moreover, the metasurface can be designed to control the leakage factor and the radiation direction. To verify the concept, two LWAs are designed to realize broadside radiation and 31° tilted radiation respectively. Compared to the same LWAs terminated with a matched load, the proposed LWAs achieve gain enhancements of 3.5 dB and 2.0 dB respectively. The proposed LWAs are fabricated and measured, the experimental results agree well with the simulated results. The proposed concept can be used to design LWAs with improved radiation efficiencies and reduced antenna lengths, which can find potential applications in various communication systems.