2-Bit Programmable Digital Metasurface for Controlling Electromagnetic wave

In this paper, a 2-bit programmable digital metasurface is designed and characterized based on the biased diode array. The metasurface contains four types of basic meta particles: '00', '01', '10', '11', with phase responses of 0, 114, 178, 304, respectively. A unique metamaterial particle that has four kinds of phase responses controlled by two biased diodes. By coding the '00', '01', '10', '11' elements with random sequences (i.e., 2-bit coding), the electromagnetic wave can be manipulated and more functionalities can be realized than 1-bit coding. We consider a programmable metasurface that contains 2x 2 equal sized lattices in which each lattice is composed of 5x 5 coding elements. Through numerical simulations, a single digital metasurface can diffuse different far field pattern.