Adaptive Field-to-Mask Procedure for the Synthesis of Metalens Antennas With Complex Near-Field Coverage Patterns in 5G Scenarios

This work presents a novel procedure to address the synthesis of metalens antennas with tight requirements in near-field complex scenarios. A model to compute the near field is introduced together with the intersection approach (IA) algorithm for metalens antennas for the first time. Then, the adaptive field-to-mask (F2M) procedure is introduced. The F2M is applied in the definition of the templates of local optimization algorithms, enhancing their convergence. F2M progressively defines the templates as intermediate solutions between the starting point and the specifications considering the radiated field behavior in each intermediate stage. The advantages of F2M are demonstrated with two examples, which synthesizes the amplitude of the near field in a challenging scenario, setting constraints in a transverse and offset plane to the metalens aperture. One of the syntheses aims to reach a uniform field distribution through a curved corridor in a range of 14 m to provide coverage at 39 GHz. The synthesized phase shift distribution is used to design and manufacture a prototype to evaluate its performance. The measurements agree with both synthesis and full-wave results. Optimization algorithms, such as IA, can take an advantage of the F2M procedure to reach hard patterns in near-field complex scenarios.