Broadband Circularly-polarized Crossed-dipole Antenna with Good Gain Stability

A broadband Circularly Polarized (CP) cross-dipole antenna with the merit of stable gain is proposed. The designed antenna consists of crossed dipoles, parasitic patches, reflectors, and vertical parasitic plates. By adding parasitic patches and parasitic plates, the circular polarization performance of the antenna is significantly improved. Furthermore, the gain value becomes stable in the entire operating frequency band by modifying the structure of the parasitic plates. The final dimension of the presented antenna is 0.76λ0 X 0.76λ0 X 0.28λ0 (λ0 is the wavelength at the center frequency point in the circularly polarized working frequency band). The measured results depict that the Impedance Bandwidth (IBW) is 80.8% (2.03GHz~4.78GHz) and the Axial Ratio Bandwidth(ARBW) is 68.5% (2.35GHz~4.8GHz). Stable gain values, ranging from 6dBic to 7.5dBic, are obtained in the working frequency band, and the average gain can reach 7dBic.