On the Use of a Metasurface Lens Over a Large-Element-Spacing Antenna Array for Grating Lobe Suppression and Gain Enhancement

The large-element-spacing (LES) antenna arrays have the advantages of low cost and less structural complexity but generally suffer from high-level grating lobes. In this paper, we propose a new method to address the issue. By placing a metasurface lens above such an LES array at an appropriate height to adjust and compensate for the phases of the near fields generated by the array, the grating lobes can be suppressed or eliminated without increasing the design complexity. Theoretical analyses, calculations from an efficient numerical method, simulations, and experiments are carried out to validate the proposed method. A complete study of the radiation performance of the proposed antenna configuration is also conducted using the above different ways. All the results demonstrate that the grating lobes from an LES antenna array can be suppressed and the gain can be improved by the proposed method at the cost of a slight increase in the antenna array profile or volume. The novel approach can be applied to any LES antenna arrays, with either large or small sizes, uniform or non-uniform spaces, and periodic or aperiodic structures.