Enhancing InSAR Accuracy for Infrastructure Monitoring: Design and Optimization of Corner Reflectors

Abstract

Monitoring critical infrastructure, such as reservoirs and dams, using Interferometric Synthetic Aperture Radar (InSAR) has been widely recognized for detecting millimeter-level displacements with comprehensive spatial and temporal coverage. This study focuses on the design and development of Corner Reflectors (CRs) optimized for C-band SAR applications to enhance the accuracy and reliability of InSAR-derived data. The CRs design considers size, radar frequency, material properties, installation conditions, and alignment adjustments to maximize signal stability and durability. A CR prototype, with a 2.4-meter base width and 1.2-meter height, constructed from 2-mm thick stainless steel, was installed at the Lam Takhong upper reservoir, under the Electricity Generating Authority of Thailand (EGAT). Field experiments confirmed that the CR effectively reflects radar signals at the C-band (5.405 GHz) and withstands environmental conditions. Proper alignment of the CRs is crucial, as even minor misalignments significantly reduce the radar cross-section (RCS). The results demonstrate that CRs are a reliable tool for calibrating Sentinel-1 SAR data, improving the accuracy of InSAR measurements. This advancement supports risk management and maintenance planning for infrastructure safety, contributing to developing a sustainable long-term monitoring system.