Precise Control for Arbitrary Polarization Based on Time Reversal Technique

This article proposes a polarization control method based on time reversal (TR) for accurately controlling any polarized electromagnetic (EM) wave. With this method, a clean polarization beam in a wide scanning range is generated without iterative optimization, and this method is not limited by radiation mechanism and array arrangement. Subsequently, the analysis elucidates how convolution effectively attenuates coupling influence during the signal TR process and how the TR technique achieves the effect of controlling arbitrary polarization. Meanwhile, the maximum achievable polarization matching gain of the current state array in the target direction is analyzed. Finally, a uniform grid planar array is used as the radiation carrier. Comparing the TR technique with the traditional equal amplitude phase-shifting feeding methods, the precise polarization control ability of the TR technique is highlighted. The comparative experiment focuses on left-handed circular polarization (LHCP), elliptical polarization, 45° oblique linear polarization, and vertical polarization (V-pol). The experimental results indicate that the TR technique effectively stabilizes the EM wave axial ratio (AR) near the expected value and reduces cross-polarization significantly, especially when scanning at large angles. This article provides a fast method with strong robustness to further enhance the accuracy and application scenarios of EM wave polarization control.