Characteristic Mode Analysis (CMA) is a powerful electromagnetic technique for understanding the natural current modes supported by an antenna structure without being influenced by the feeding network. In circularly polarized (CP) antenna design, CMA is especially useful for identifying two orthogonal characteristic modes with comparable modal significance and the required phase relationship for CP radiation. By studying parameters such as eigenvalues, characteristic angles, modal significance, and surface current distributions, designers can systematically control the antenna modes to improve axial-ratio bandwidth, polarization purity, and radiation performance. CMA therefore provides a physics-based approach to CP antenna design, reducing dependence on conventional trial-and-error optimization.