Novel Corner-Reflector Array Application in Essential Infrastructure Monitoring

Abstract

High precision monitoring of infrastructure using 1 artificial reflectors is possible with freely available Sentinel-1 2 data, but large reflectors are needed. We find that a triangular 3 trihedral corner reflector should typically have at least 1 m inner 4 leg length. 5 As such large reflectors are often not feasible for use in urban 6 areas for essential infrastructure monitoring, we designed a 7 multiple corner-reflector array to replace a single corner reflector 8 with an inner leg length of 1 m. In this case, we use four reflectors 9 where each of them is a truncated triangular trihedral with an 10 inner leg length of 0.33 m. We measured InSAR amplitude, phase 11 and coherence of this reflector array with various configurations 12 of alignments of the array. We find that as long as great care 13 is taken in the relative positioning of the four corner reflectors, 14 so that they constructively interfere, each horizontal or vertical 15 configuration provides the expected amplitude, coherence and 16 phase stability.17Applications of multiple small corner reflectors in urban 18 areas range from essential infrastructure monitoring (e.g bridges, 19 overpasses, tunnel constructions), through assessment of struc-20 tural health of buildings, to monitoring highway and railway 21 embankments. We show that the multiple corner array works 22 when placed in a single InSAR resolution cell, but depending on 23 the application, the number and projection of corner reflectors 24 can be varied, as long as sufficient signal-to-clutter ratio is 25 achieved in the area of interest. 26 Index Terms-Corner Reflectors, InSAR, Infrastructure mon-27 itoring 28 I. INTRODUCTION 29 O UR ever-expanding structural infrastructure is in con-30 stant need of monitoring and maintenance due to damage 31 from regular use and exposure to natural processes. It is near-32 impossible to manually inspect all bridges, railways, highways, 33 and other essential infrastructure to predict and avoid failures 34 that might result in loss of life and great economic losses. 35 Recent advances in various remote sensing methods have 36 improved our capabilities to monitor large areas with various 37 techniques of different temporal and spatial resolutions.38 In particular, Interferometric Synthetic Aperture Radar (In-39 SAR) is being widely used for ground motion detection for 40 various applications ranging from world-wide natural haz-41 ard monitoring (e.g. [1]), and early warning (e.g. [2], [3]) 42 through nation-wide infrastructure and land observation (e.g.43 [4], [5]) to small-scale studies of local deformations (e.g.

Double-Notch Frequency-Coded Corner Reflectors for sub-THz Chipless RFID Tags

“…Corner reflectors (CRs) have been considered as chipless RFID tags in multiple applications within the mm-wave frequency range, due to their low complexity and well-known and large backscattered response. For example, they are found in works dealing with smart environments [1], [2], maritime [3] and unmanned aerial vehicles applications [4] and automotive radar [5], [6], to name a few. Particularly in the case of indoor self-localization, sub-THz (100 GHz to 300 GHz) systems present a good trade-off between microwave's deep penetration capabilities through non-metallic materials and the fine spatial and time resolution of the optical frequency range, resulting in millimeter positioning accuracy [7] [8], while enabling nonline of sight applications [9], [10].…”