Abstract-In this paper, a dual-band circularly polarized (CP) patch antenna with left-hand circular polarization (LHCP) in the lower band and right-hand circular polarization (RHCP) in the higher band is proposed. On the basis of aperture coupled feed, the dual-band circular polarizations are achieved by adopting two rectangular patches with different rotation angles on the front and back of a substrate. A good agreement between the simulated and measured results is obtained. The 10-dB impedance bandwidths and 3 dB Axial Ratio (AR) bandwidths are 18.4% (1.93-2.32 GHz) and 3.2% (2.14-2.21 GHz) in the lower band and 12.4% (2.58-2.92 GHz) and 1.7% (2.84-2.89 GHz) in the higher band, respectively. The proposed antenna with its simple structure, compact size and excellent performance provides a reference for communication system applications.