A novel design concept to widen axial-ratio (AR)-bandwidth of a single circularly polarized (CP) patch antenna is presented by resonating its TM1/2,0, TM1/2,1, and TM3/2,0 modes. First, a set of shorting pins is loaded around the edge of the patch with decreased width, aiming to suppress undesired nonbroadside modes. Second, the far-zone radiated fields of the antenna are theoretically studied by using equivalent magnetic currents (EMCs). The results demonstrate that its broadside |Eθ|, |Eφ|, and -|Eθ|components of xo z plane radiation patterns could be orthogonally generated under TM1/2,0, TM1/2,1, and TM3/2,0 modes, respectively. Most importantly, these three broadside EMCs must be sequentially rotated. Third, the resonant frequencies of these triple radiative modes ( f1/2,0, f1/2,1, and f3/2,0 ) are extensively analyzed and reallocated by loading the shorting pins. It proves that the f1/2,0 and f1/2,1 could be progressively pushed up to around the f3/2,0, resulting in generating the CP radiation as expected. With these arrangements, the AR-bandwidth of the proposed CP antenna is significantly widened under triple-mode resonance. In final, the proposed antenna is fabricated and measured. Simulated and measured results are in good agreement with each other. The measured results depict that the CP antenna has acquired an enhanced AR-bandwidth with two minima poles, covering a fractional bandwidth of about 5% from 3.25 to 3.41 GHz, which is about 3.3 times wider than the traditional counterpart (1.5%). Besides, its profile is kept only about 0.03 free-space wavelength. Particularly, the single-layer, single-fed, single-radiator, and high-efficiency properties are simultaneously maintained for the CP antenna without needing to rely on any extra feeding networks, patches, or resisters.