Wideband Multiport Antenna Design by Sub-Array Aperture Sharing Offering Dual-Circularly Polarized Beamforming for Wireless Power Transfer

This work proposes a low-cost, low-profile, and wideband antenna with the capability of dual-circularly polarized (DCP) radiation. The design concept utilizes a common and shared sub-array aperture for both circularly polarized (CP) states, achieving competitive performances. The basic structure comprises five patch elements and the first state, CP1, is achieved by a central patch, while the second state, CP2, is made possible by the placement of four surrounding patches. Sequential rotation is employed and this realizes polarization purity in terms of low axial ratios and cross-polarization levels. In addition, the design lends itself to larger scale arrays as reported in this letter. The measured results for the fabricated prototype are in agreement with the simulations, demonstrating an impressive impedance bandwidth (BW) of about 22.8% for both states (2.23 to 2.80 GHz) and a 3-dB axial ratio (AR)-BW of 24.6% (2.21 to 2.83 GHz). In addition, the antenna is simple and can be a suitable candidate for satellite systems and wireless communications, and generally where DCP is required. As further outlined in the letter, the proposed multiport design can also be useful for DCP wireless power transfer systems which operate on array principles.