A 28 GHz Double Patch Double Beam Antenna with Circular Polarization for Energy Harvesting

This paper presents the design of a double-patch, double-beam directional microstrip patch antenna, with circular polarization and enhanced bandwidth. The antenna design was accomplished by first creating a square patch resonating at the desired frequency. Subsequently, the ground plane was replaced by a second patch, identical to the initially designed one, resulting in a significant back lobe, nearly equivalent in size to the main lobe. Additionally, cuts were made at the corners of the patches to enhance antenna bandwidth and achieve circular polarization. This resulted in an antenna with an enhanced bandwidth of $\mathbf{1 . 6 9}$ $\mathbf{G H z}$ (27.17-28.86 GHz), covering the 28 GHz band (27.5-28.35 GHz). Moreover, it exhibits circular polarization within the frequency range of 27.88 GHz to 28.09 GHz, and a gain of 6.03 dBi for the principal lobe. The back one attains a comparable value. The antenna achieves an efficiency of $\mathbf{9 0 \%}$. The antenna size is $0.31 \lambda_{0} \times 0.31 \lambda_{0}$.