Abstract: An aperture-shared dual-band dual-circularly polarized dielectric resonator antenna (DRA) is proposed for ground terminals in response to the demand for high-speed frequency division duplex communication in satellite internet. By embedding the high-frequency cylindrical dielectric resonators into the low-frequency annular cylindrical dielectric resonators, the aperture-shared function is achieved. Using the dual-probe method to excite the degenerate mode inside the dielectric resonator, orthogonal circularly polarized waves are generated at low and high frequencies by controlling the phase difference between the degenerate modes. In order to weaken the electromagnetic coupling between different frequencies, the thickness of the circular cylindrical dielectric resonator was optimized to effectively solve the problem of low-frequency pattern distortion and improve impedance matching. Furthermore, a 2×2 antenna array was established based on the sequential rotation method, and a prototype was manufactured and measured. The results show that the operating bandwidth of low-frequency left-handed circular polarization (LHCP) is 25.5% (14.4 GHz-18.6 GHz), and high-frequency right-handed circular polarization (RHCP) is 6.5% (26.8 GHz-28.6 GHz). The miniaturization characteristics and stable radiation performance of this aperture-shared antenna can be applied to satellite communication equipment such as in vehicle and airborne systems.