Physics Practical Magic

A new 'smart skin' for rooms can bend radar waves to see heartbeats and movements hidden in shadows or around corners.

March 31, 2026

Original Paper

Radar Cross Section Characterization of Quantized Reconfigurable Intelligent Surfaces

Kainat Yasmeen, Shobha Sundar Ram, Debidas Kundu

arXiv · 2603.27961

The Takeaway

Traditional radar can only see what is directly in its line of sight, much like a flashlight. Researchers developed a programmable surface that can 're-program' electromagnetic waves to bounce into hidden areas, allowing it to recover data from 'invisible' regions and even detect tiny vibrations like a human pulse where conventional radar would see nothing.

From the abstract

We present a radar sensing framework based on a low-complexity, quantized reconfigurable intelligent surface (RIS) that enables programmable manipulation of electromagnetic wavefronts for enhanced detection in non-specular and shadowed regions. We develop closed-form expressions for the scattered field and radar cross section (RCS) of phase-quantized RIS apertures based on aperture field theory, accurately capturing the effects of quantized phase, periodicity, and grating lobes on radar detectio