Abstract: A compact dual-circularly-polarized active receiving antenna is designed for S-band applications, which integrates a microstrip patch antenna with a 90° hybrid bridge and low noise amplifiers. The proposed active receiving antenna not only achieves the miniaturization of the antenna but also improves the connection efficiency among each device. Meanwhile, the antenna is probe-fed by glass insulators through a semi-differential method which improves the symmetry of the antenna radiation pattern and simplifies the structure of conventional differential feeding method. The simulated and measured results show that the voltage standing wave ratio(VSWR) of the active receiving antenna is less than 1.47, the noise figure is less than 0.75 dB, the axis ratio within the main lobe is less than 2.4 dB, and the G/T value is greater than -13.9 dB/K from 2.2 to 2.3 GHz. The G/T value of the antenna is greatly improved compared with existing active receiving antennas.