High-Efficiency Leaky Wave Antenna Based on Periodic Field-Distribution Modulation of Single-Conductor Comb Lines

Deep subwavelength periodic structures support the efficient propagation of highly bounded surface electromagnetic (EM) waves, whereas leaky wave radiation requires secondary periodic modulation to enable wireless communication. However, the commonly used surface impedance modulation (SIM) method usually has the disadvantage of low leaky wave efficiency. In this communication, we apply the field-distribution modulation (FDM) method to help improve the radiation efficiency of the leaky wave antennas (LWAs) by periodically designing the discontinuity of electric-field distributions between two deep subwavelength periodic transmission lines (TLs). Specifically, we guide a pair of surface EM waves with electric fields concentrated on each side of the midline using two segments of single-conductor comb lines (SCCLs) with opposite grooving directions and achieve the effective leaky wave radiations by their interleaved arrangements to form a periodic field-distribution mismatch. Simulation and measurement results show that the FDM-assisted SIM SCCL LWAs can break through the modulated limitation of pure SIM and have a better performance in terms of radiation efficiency. Finally, we solve the low-efficiency problem that usually occurs in amplitude-weighted low sidelobe LWAs using the FDM method, and achieve the SCCL LWA with high efficiency and low sidelobe characteristics. These results indicate that the FDM method is expected to achieve more efficient leaky wave radiations of highly bounded surface EM waves.