Modeling and Prototyping of Unit Cell for Reconfigurable Intelligent Surface: Electromagnetic Model, Design and Circuitry

This paper presents the design and experimental implementation of a 1-bit unit cell for a reconfigurable intelligent surface operating in the 2.4 GHz band. The primary objective of our work is to investigate control and channel estimation techniques for the reconfigurable intelligent surface communication channel. To conduct the experiment, it is necessary to develop a reconfigurable intelligent surface, which, in turn, requires designing a unit cell. The proposed unit cell is based on a rectangular patch antenna with a PIN diode, enabling phase control of the reflected signal by switching between forward and reverse bias (ON and OFF) states. the reflection coefficient is analyzed in an electromagnetic simulator with periodic boundary conditions. A prototype is fabricated on a double-layer printed circuit board using FR-4 material. Experimental measurements, conducted with a vector network analyzer, confirmed a phase difference of 118° between the ON and OFF states at the target frequency. The results validate the proposed design as a unit cell for reconfigurable intelligent surfaces in wireless communication systems. The contribution of this work is to expand theoretical and practical base in the field of reconfigurable intelligent surface, which, in turn, can help accelerate the implementation of this technology in existing and future wireless systems.