The main difference is in radiation pattern, isolation, and spatial diversity. A pentagon-shaped substrate with MIMO antennas arranged radially provides better isolation, lower mutual coupling, and omnidirectional coverage. A rectangular-shaped substrate usually supports linear or planar arrays, offering directional radiation but higher coupling.

MIMO antennas placed on a pentagon-shaped substrate can provide omnidirectional (360°) coverage and angular diversity while potentially reducing mutual coupling between elements, this configuration is advantageous in applications requiring symmetric coverage. In contrast, a rectangular substrate with regular placement is more suitable for directional beamforming and achieving high gain, it is also easier to manufacture and more compatible with conventional MIMO implementations.