Low-profile Broadband Radiation-type Programmable Metasurface Unit

The programmable metasurface can flexibly manipulate electromagnetic (EM) waves by the spatial distribution of digital coding. This paper presents a low-profile broadband radiation-type programmable metasurface unit to control EM waves in C band. Meanwhile, the proposed radiation-type metasurface has much lower profile comparing with the reflective or transmissive metasurface. The unit contains two PIN diodes which can produce phase responses of 0 and $\pi$ by changing the states of PIN diode. The proposed metasurface can realize different far-field radiation patterns by designing different coding sequence for PIN diodes.