Circularly polarized broadband patch antenna for wireless communication

In this paper, the design of a new printed circularly polarized (CP) antenna with an octave operating bandwidth is presented. The design technique is different from conventional monopole/dipole antenna. The antenna has a microstrip-fed line of rectangular radiator printed on RT/Duroid substrate with the total dimension of 106 mm × 60 mm × 1.57 mm. In the bottom, another rectangular radiator is printed which act as a ground. The upper and bottom radiators are both constituted in asymmetric feeding so that the surface current generate left-hand circular polarization (LHCP) orthogonally. The design is simulated in HFSS simulation solver and the properties are carefully analyzed to verify the antenna characteristics. The simulated result shows the bandwidth of 960 MHz to 2.60 GHz under a 10-dB return loss and axial ratio bandwidth of 2 GHz to 5 GHz at 3-dB. With a stable gain of 4.2 dB the antenna shows circular polarization. A parametric study of the surface current distribution and the mechanism of CP is analyzed.