Design Approach of PIN-Diode Driven Reconfigurable Reflective Electromagnetic Surface with Isolated Biasing Network

Abstract

This paper discusses the design approach of PIN-diode driven reconfigurable reflective electromagnetic surface (RRES) capable of switchable linear-to-circular polarization conversion at the frequency of 2.3 GHz. The unit cell of RRES utilizes a square patch with a diagonal slot, modified with a rectangular strip to accommodate six PIN-diodes. A multi-layer technique is implemented, where the direct current (DC) line of biasing network is isolated on a separated layer beneath the groundplane to minimize electromagnetic interference. Simulations using an equivalent circuit model of BAR64 type PIN-diode demonstrate that the proposed RRES can be dynamically switched between the ON-state, which maintains a linearly polarized incident wave, and the OFF-state, which converts a linearly polarized incident wave into a circularly polarized reflected wave. The functionality is evaluated through a $3 \times 3$ element array simulation, confirming that the isolated biasing network and finite element array maintain high polarization purity. This design approach provides a practical framework for polarization control in future reconfigurable intelligent surface (RIS) applications.