Compact Ultra-wideband Circularly Polarized Stacked Patch Antenna

In this paper, a wideband circularly polarized (CP) stacked patch antenna is proposed. Three substrate layers are employed in the presented design. A novel 90 degrees broadband microstrip balun, printed on the back side of the lower substrate, is utilized to feed the CP stacked antenna. The loop feeding network with four rectangle stubs is excited by twin probes associated with the broadband balun. Four weakly coupled sequentially rotated symmetric hexagonal patches are designed as radiation patches. From the simulated results, it is showed that the proposed antenna exhibits a 10-dB impedance bandwidth of 76.2% (1.64-3.66 GHz), 3-dB axial ratio bandwidth of 81.6% (1.43-3.40 GHz), and a peak gain of 6.74 dBi at 2.0 GHz.