Millimeter-Wave RIS: Hardware Design and System-Level Considerations

TL;DR

This paper reviews recent hardware design advancements for millimeter-wave reconfigurable intelligent surfaces, emphasizing practical implementation challenges and system-level considerations to guide scalable and efficient deployment.

Contribution

It provides a comprehensive hardware-centric overview of mm-Wave RIS developments, highlighting design choices, challenges, and system implications for future research.

Findings

Discusses wideband and high-resolution phase-quantized designs

Highlights challenges like mutual coupling and calibration

Provides practical insights for scalable RIS deployment

Abstract

Reconfigurable intelligent surfaces have emerged as a promising hardware platform for shaping wireless propagation environments at millimeter-wave (mm-Wave) frequencies and beyond. While many existing studies emphasize channel modeling and signal processing, practical RIS deployment is fundamentally governed by hardware design choices and their system-level implications. This paper presents a hardware-centric overview of recent mm-Wave RIS developments, covering wideband realizations, high-resolution phase-quantized designs, fully printed low-cost implementations, optically transparent surfaces, RIS-on-chip solutions, and emerging three-dimensional architectures. Key challenges including mutual coupling, calibration, multi-RIS interaction, and frequency-dependent phase control are discussed to bridge hardware realization with system-level optimization. This overview provides practical design insights and aims to guide future RIS research toward scalable, efficient, and practically deployable intelligent surface architectures.