Amplitude-Phase Co-Modulation Radiation-Type Programmable Metasurface for Intelligent IoT Applications

Programmable metasurface based on the design philosophy of information metasurfaces have attracted widespread attention in Internet of Things (IoT) in recent years due to their advantages of low cost and low complexity. However, most existing radiation-type programmable metasurface are either phase-only coding or amplitude-only coding, which limits their functionality and applications. Here, we propose a high-performance 1-bit radiation-type programmable metasurface with amplitude-phase co-modulation. By adjusting two PIN diodes integrated on each meta-atom, the phase and amplitude can be controlled separately. The meta-atom phase can switch between two states with a phase difference of 180°, with the PIN diode states being 01 and 10 (where 1 represents ON and 0 represents OFF), respectively. The amplitude can be switched between two states, reflection, and radiation, with the PIN diode states being 00/11 and 01/10, respectively. In addition, the meta-atom can acquire an initial phase by rotating within the plane. An $8\times 8$ programmable metasurface is given to verify its functionality. First, the initial phase can be used for suppressing grating lobes of the 1-bit radiation-type programmable metasurface. Second, through amplitude-phase co-modulation, the beam amplitude can be controlled dynamically, including the main lobe and the sidelobe. Therefore, the high performance 1-bit radiation-type programmable can serve as a promising candidate for intelligent IoT applications, including smart city, home, factory, and more.