Gain Enhancement of Dual-Polarized 2-D Multibeam Antenna With Transmitarray

A novel phase compensation method for the design of transmitarray is proposed in this article, enabling the gain enhancement for a dual-polarized 2-D multibeam antenna for the first time. The multibeam antenna is implemented in three-stacked printed circuit board laminates. Two sets of Butler matrices in substrate integrated waveguide (SIW) technology are vertically placed at different layers to feed the upper <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2\times 2$ </tex-math></inline-formula> dual-polarized magneto-electric (ME) dipole antenna array. To verify the proposed method, a transmitarray employing the novel phase compensation method is designed as an overlay, consisting of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$40\times 40$ </tex-math></inline-formula> single-layer dual-polarized unit cells. Finally, the whole high-gain 2-D multibeam antenna operating at the center frequency of 26 GHz is simulated and experimentally validated. The measured -10-dB impedance bandwidth achieves more than 23.1%, and the measured peak gain is 17.8 dBi for x-polarization and 17.9 dBi for y-polarization. The proposed transmitarray provides a maximum gain enhancement of 8.8 dB at 26 GHz. The measurements are in good agreement with the simulation results. The proposed method is general to other multibeam antennas of arbitrary scale for 5G millimeter-wave (mmWave) applications.