Initial Experimental Demonstration of Microwave Imaging for Mapping Leakage-Induced Subsurface Anomalies

Abstract

The detection and spatial assessment of buried water pipeline leaks are critical for preventing resource loss and geohazards such as soil erosion and subsidence. This paper presents an initial experimental demonstration of a microwave imaging system designed for mapping subsurface anomalies induced by buried water pipeline leaks. The proposed system integrates a custom-designed broadband open-sleeve dipole antenna with a vector network analyzer, power amplifier, and a precision linear motion stage that emulates synthetic aperture radar scanning for controlled measurement validation. The antenna achieves a 66.7% impedance bandwidth (1∼2 GHz) and a stable gain of approximately 8 dBi. A phase-compensated back-projection algorithm is employed to generate two-dimensional ground-projected scattering maps. Controlled experiments involving wet-sand regions, surface potholes, and subsurface cavity surrogates yield averaged within-image response differences of 2.1∼5.2 dB between anomaly-associated regions and ground background regions. Under the specified acquisition conditions, the theoretical azimuth and range resolutions are 0.28 m and 0.15 m, respectively. These results provide preliminary evidence of imaging feasibility under the tested surrogate-target conditions. Further validation with actual leakage and representative soil and surface-cover conditions is required to assess applicability to infrastructure monitoring.