S-band Dual Circularly Polarized Microstrip Patch Antenna Array for Satellite Communication

A dual circular polarized microstrip patch antenna array in S band is presented with high gain, low sidelobe and low cross polarization, which can readily be applied for satellite communication. The antenna array is composed of four 2 x 2 subarrays, two feed networks and a 3dB coupler. The dual linear polarized elements fed with the 180 degrees phase shift to decrease the cross polarization. The two feed networks are implemented on two stacked substrates and connected by the 3dB coupler to achieve dual circular polarizations. The array is fabricated and measured. The measured results agree with the simulated results well. The return loss is better than 25dB, and the isolation is more than 20dB over the operating band. In addition, the cross polarization greater than 25dB and gain more than 18.8 dB for both LHCP and RHCP are obtained.