An Experimental Validation of Reconfigurable Intelligent Surfaces Achieving Pulse Width-Modulated Singular Reflection Angles Without External Power Sources

TL;DR

This paper presents a passive reconfigurable intelligent surface that switches reflection angles based on pulse width without external power, validated through experiments and capable of significantly altering wave magnitude and communication signals.

Contribution

It introduces a novel passive RIS design that uses pulse width variation for reconfiguration, eliminating active components and synchronization requirements.

Findings

Achieves a tenfold variation in received wave magnitude.

Experimentally validates pulse width-dependent reflection switching.

Modulates communication signals by over 7 dB using BPSK.

Abstract

In this study, we introduce a design concept that leverages pulse width variation to enable a reconfigurable intelligent surface (RIS) and to autonomously switch reflection properties between two angles without any active control system. Our RIS alters its beam pattern from a singular specular reflection to another unique singular anomalous reflection when the incoming waveform changes from a short pulse to a continuous wave, even at the same frequency. Unlike conventional RISs, our passive control mechanism eliminates the requirements of active components and precise symbol-level synchronization with the transmitting antennas, reducing the system complexity level while offering dynamic material adaptability. We numerically show that the proposed RIS design is capable of varying the received magnitude of an incident wave by a factor of ten, which is also experimentally validated for the first time. Employing binary phase-shift keying (BPSK) modulation, we further report that the communication characteristics can be varied by 7 dB or more, which indicates that the proposed design is not limited to a single frequency component as long as the bandwidth of the given signal is covered by that of the RIS design. These results may present new opportunities for exploring and deploying pulse width-dependent RISs in practical scenarios involving next-generation communication systems.