A novel design concept to excite and produce the broadside circularly polarized (CP) radiation is presented in a shorted-patch antenna (SPA). First, the far-zone radiated fields of the SPA under radiation of TM and TM modes are theoretically studied. It demonstrates that the broadside |E| component of its TM mode is generated in yoz plane. In contrast, the orthogonal |E| component of its TM mode is produced in this plane. Then, the resonant frequency of the TM mode is gradually pushed up to around that of TM mode, aiming to generate the normal CP radiation between these dual modes. After that, a linear slot is etched out on the core radiator so as to counteract the equivalent inductance caused by the loaded pins and feeding probe. Finally, the proposed antenna is fabricated and tested. The measured results reveal that it's operating bandwidth (|S|<-10 dB and AR<3 dB) is kept at about 1.2% or at a range of 2.720-2.752 GHz. Most importantly, the CP radiation (AR<3 dB) of the antenna at the broadside direction is indeed resonated at around 2.738 GHz, while keeping the reduced length, single-layer, and single-fed properties.