Design and Prototyping of Filtering Active STAR-RIS with Adjustable Power Splitting

TL;DR

This paper introduces an active STAR-RIS with adjustable power splitting and harmonic suppression, enhancing signal strength and flexibility for next-generation wireless systems by integrating active amplification and dynamic power control.

Contribution

It proposes a novel active STAR-RIS design with independent phase control, out-of-band harmonic suppression, and dynamic power allocation, advancing beyond traditional passive RIS technologies.

Findings

Enhanced signal strength through active amplification.

Supports dynamic power allocation between modes.

Validated with extended RCS-based path loss model.

Abstract

Reconfigurable Intelligent Surfaces (RISs) have emerged as a transformative technology for next-generation wireless communication systems, offering unprecedented control over electromagnetic wave propagation. In particular, Simultaneously Transmitting and Reflecting RISs (STAR-RISs) have garnered significant attention due to their full-space coverage. This paper presents an active STAR-RIS, which enables independent control of both transmission and reflection phases and features out-of-band harmonic suppression. Unlike the traditional passive RIS, the proposed design integrates active amplification to overcome the inherent passive losses, significantly enhancing signal strength and system performance. Additionally, the system supports dynamic power allocation between transmission and reflection modes, providing greater flexibility to meet diverse communication demands in complex propagation environments. The versatility of the design is further validated by extending the Radar Cross Section (RCS)-based path loss model to the STAR-RIS. This design improves efficiency, flexibility, and adaptability, offering a promising solution for future wireless communication systems, particularly in scenarios requiring simultaneous control of transmission and reflection signals.