Impact Analysis of Realistic Antennas on the Performance Metrics of Electromagnetic Degree of Freedom and Channel Capacity in Near-Field Environments

This paper presents a comprehensive analysis of the impact of realistic antenna configurations on key performance metrics in near-field MIMO wireless communication environments. The study focuses on the Electromagnetic Degree of Freedom (EDOF) and channel capacity, comparing four antenna types: isotropic, dipole, patch, and plane wave models. A MIMO system with a 16×16 planar array for the base station at 3GHz and a 4×4×4 cubic array for the User Equipment (UE) is simulated. The analysis considers both linear and circular UE movement patterns and examines antenna spacings ranging from 0.25λ to 2.00λ. A detailed electromagnetic (EM) channel model based on the dyadic Green's function is employed, incorporating mutual coupling effects for accurate performance estimation in both near-field and far-field regimes. The results reveal significant variations in EDOF and capacity across different antenna configurations and movement patterns. Patch antennas demonstrate superior peak performance, particularly at larger spacings, but with increased variability across UE positions. The study highlights the limitations of the plane wave model in near-field scenarios and provides insights into the trade-offs between peak performance and consistency. These findings offer valuable guidance for the design and optimization of MIMO systems in emerging near-field applications, addressing considerations for antenna selection, spacing, and UE mobility patterns.