Asymmetric Harmonic Manipulation of Electromagnetic Wave by 2-bit Time-varying Coding Metasurface

In this paper, we propose a 2-bit time-varying coding metasurface loaded with PIN diodes for achieving asymmetric harmonic manipulations of electromagnetic wave (EM). As a proof of the concept, predesigned periodic time-varying coding sequences are applied onto the metasurface to enable the efficient control of $+1^{\mathrm{s}\mathrm{t}}, +2^{\mathrm{n}\mathrm{d}}$, and -$2^{\mathrm{n}\mathrm{d}}$ order harmonics. The proposed metasurface may have potential uses in frequency multiplexing techniques and wireless communication applications.