Analysis of Performance Improvement of Planar Antenna Arrays with Optimized Square Rings for Massive MIMO Applications

Abstract

The radiation pattern of conventional fully optimized planar arrays can be effectively reshaped according to user-defined constraints. However, the practical implementation of such fully optimized large planar arrays is complex and costly. This paper introduces a novel and efficient technique capable of delivering comparable performance and nearly identical radiation patterns to those of conventional fully optimized planar arrays. This is achieved by optimally adjusting only the excitation amplitudes and phases of elements located in the outer square rings, rather than adjusting all elements. The proposed technique begins with a large fully populated planar array, which is then divided into two contiguous sub-arrays symmetric about the array center. Only the excitation amplitudes or phases of the outer sub-array elements are adjusted to achieve the desired radiation pattern shape. In contrast, the excitation amplitudes or phases of the central sub-array elements—which typically have higher weighting—are held constant (i.e., set to unity for amplitude-only control, and to zero for phase-only control). The results demonstrate that the proposed planar array can form required radiation patterns using a significantly smaller number of adjustable elements.