A Compact Broadband Circularly Polarized Crossed-Dipole Antenna With a Very Low Profile

Abstract

A low-profile wideband circularly polarized (CP) crossed-dipole antenna with eight parasitic elements is presented. The parasitic elements are located on the top and bottom surfaces of the same substrate printing the crossed dipoles, and each consists of a horizontal patch and a vertical shorting pin. It has been found that the introduction of the four parasitic shorted patches on the bottom surface of the substrate can enhance the bandwidth and reduce the profile of the antenna, while the four parasitic shorted patches on the top surface of the substrate can further increase the axial-ratio (AR) bandwidth and improve the boresight gain, leading to a low-profile wideband CP antenna with stable in-band gain. For validation, a prototype was fabricated and measured. The measured results demonstrate that the proposed antenna has a profile of as low as 0.067 λ ₀ , a -10 dB impedance bandwidth of 61.8%, a 3 dB AR bandwidth of 51.6%, and a gain fluctuation of 1.2 dB within the overlapping passband.