A Systematic Approach for Determining Transmitarray Specifications in Near-Field Scenarios

Manipulating near-field electromagnetic wavefronts is crucial for hyperthermia, compact test range systems and wireless power transmission. This paper investigates a design methodology of transmitarrays for near-field wavefront shaping. Unlike conventional methods that rely on trial and error or optimisation procedures, this approach establishes practical relationships to determine transmitarray specifications. At first, the achievable resolution is calculated based on the observation distance. Then, transmitarray specifications are calculated based on the number of observation points, observation distance and achievable resolution. This methodology enables a swift and precise design process by integrating the Moore–Penrose inverse technique and dyadic Green's functions (DGFs). Detailed examples demonstrate the effectiveness of this approach, achieving desired electromagnetic patterns while reducing complexities and design iterations. This work significantly advances the understanding and practical implementation of near-field shaping techniques, particularly for applications requiring tailored electromagnetic patterns. Analytical and experimental results rigorously validate the problem formulation, confirming the proposed algorithm's capability and highlighting its potential for widespread application.