Harmonic Beam Steering with 2-Bit Equivalent Phases Using a 1-Bit Time-Domain Coding Metasurface

This paper presents harmonic beam steering by employing 2 -bit equivalent phases from a 1 -bit time-coding element. The space-time-coding (STC) matrix is computed based on the fundamental frequency ($f_{c}$), the desired m th harmonic, and the desired beam angle ($\theta_{d}$). Scattering pattern plots illustrate the radiation pattern at $\theta_{d}$ for the frequency $f_{c}+m f_{0}$, and at $-\theta_{d}$ for $f_{c}-m f_{0}$, where $f_{0}$ is the modulation frequency. The symmetry observed in the radiation patterns for $\pm m$ th harmonics is attributed to the symmetry between their corresponding optimized 2-bit phase equivalents. However, while using the original 1-bit STC matrix, each harmonic produces symmetrically deflected dual beams directed at $\pm \theta_{d}$. The proposed concept and design can be applied to millimeter-wave (mmWave) sensing, communications, and imaging.