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

Abstract

AbstractA 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.