Axial‐ratio beamwidth and gain enhanced circularly polarized antenna using parasitic elements

A circularly polarized (CP) crossed-dipole antenna with enhanced 3-dB axial ratio (AR) beamwidth and gain via the addition of parasitic elements is proposed in this letter. First, a simplified CP crossed-dipole model loaded with four parasitic elements is constructed to investigate the principle of wide axial-ratio beamwidth. Theoretical analysis shows that by choosing the length and position of these parasitic elements properly, the 3 dB AR beamwidth of the simplified CP antenna can be enhanced significantly. Then, a practical CP crossed-dipole antenna designed at 1.575 GHz is utilized to verify the feasibility of this method. Experimental results are in a good agreement with the simulated ones in terms of radiation pattern, gain, AR and |S11| for the proposed antenna. In particular, due to the addition of the four parasitic elements, the 3 dB AR beamwidth of the antenna at the central frequency of 1.575 GHz is increased from 72° to 134°; the gain in the working frequency bandwidth also shows an increase of almost 3 dBi when these parasitic elements are added.