This paper presents a low profile and low-cost patch antenna with dual circularly polarized (CP) capability in X-band at a canter frequency of 8.3 GHz. The dual-CP antenna is divided into three layers, composed of a parasitic square patch, radiation square patch with four equal arms, and 90˚ patch coupler. Two arms of the radiation patch are connected to the 90˚ hybrid coupler using two metalized vias. right-handed circular polarization (RHCP) and Left-handed circular polarization (LHCP) is achieved by exciting two different ports. To validate the proposed design, the prototype of dual-CP antenna is fabricated and measured. Based on the measurement, the structure of proposed antenna has an excellent circular-polarization purity of less than 3-dB over the whole operational frequency bandwidth of the antenna (8 GHz-8.47 GHz) with a wide 3-dB axial ratio (AR) beamwidth of 133˚ across the angular range from -55° to +78° at 8.3 GHz.
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