Engineering sustainable periodic surfaces for cutting-edge radomes in SAR-based ETA systems

This work presents a compact, low-cost, and sustainable metaradome solution for wearable millimeter-wave radar antennas operating at 24 GHz, aimed at Electronic Travel Aid (ETA) systems for visually impaired individuals. To protect a microstrip Grid Array Antenna (GAA) without compromising performance, three different metaradome metallization geometries—cross, hexagon, and circle—are proposed and evaluated. The GAA and the metaradomes are fabricated using aluminum-cladded polypropylene (PP), a sustainable and recyclable material and standard PCB milling techniques. A comprehensive electromagnetic analysis is conducted, including impedance matching, radiation characteristics, and angular stability, both in simulation and measurement. Results demonstrate that the metaradomes can significantly outperform conventional radomes in terms of transmission, reflection, and radiation efficiency, while maintaining compactness and mechanical robustness. The proposed metaradome-antenna ensembles achieve high gain (up to 14 dBi), wide beamwidths (≥ 30°), and high efficiency (up to 93%), meeting the requirements for short-to-medium range radar sensing in wearable applications. Furthermore, an analysis of the influence of metaradome metallization geometries on the phase of the radiation pattern is incorporated—an aspect not previously investigated, despite the critical importance of phase integrity for SAR image quality. This contribution advances the state of the art by integrating sustainable materials and metaradome engineering into high-performance, wearable radar systems, paving the way for greener and more resilient assistive technologies.