A Wideband Low-Profile Efficiency-Improved Transmitarray Antenna With Over-1-bit Phase-Shifting Elements

This paper describes a wideband, low-profile and efficiency-improved transmitarray antenna achieved by employing over-1-bit phase-shifting elements and incorporating optimized phase compensation scheme. Firstly, a wideband ultrathin 1-bit phase-shifting unit cell is presented based on the polarization twisting feature of the twisted stacking aperture structure. A minor variation in unit-cell geometry is then introduced to add more degrees of freedom in phase adjustment while maintaining nearly same low insertion loss within a wide frequency range. Moreover, the resultant performances of transmitarrays using different phase compensation schemes are compared. An optimized scheme that has a minimized average phase error and effectively enhances the aperture efficiency is adopted. Results of a 21.5% 1-dB gain bandwidth, 0.127-λ
₀
aperture thickness and 40% aperture efficiency are observed from the fabricated 14 × 14 transmitarray antenna.