Signal Loss, Spatial Resolution, and Sensitivity of Long Coaxial Crack Sensors


Configuration-based coaxial cable sensors have recently been developed to detect cracks in reinforced concrete (RC) structures. These sensors have shown a high sensitivity when applied to several short RC flexural members. However, the signal losses resulting from a long cable sensor may distort the initial waveform of the electromagnetic wave propagating along the cable, thereby compromising the spatial resolution and sensitivity of this sensor. The signal losses consist of the contributions from the skin effect of conductors, energy absorption in the dielectric material, and impedance mismatch loss due to multiple signal reflections resulting from discontinuities caused by the separation between the adjacent spirals, which acts as the outer conductor of a cable sensor. This paper summarizes the basic physics of signal losses in cable sensors, and investigates the impact of the signal losses on the spatial resolution and sensitivity of a cable sensor over distance. Several methods are proposed to simulate and quantify various factors affecting the signal losses.

Meeting Name

Smart Structures and Materials (2004: Mar. 14-18, San Diego, CA)


Civil, Architectural and Environmental Engineering

Second Department

Electrical and Computer Engineering

Third Department

Materials Science and Engineering

Keywords and Phrases

Coaxial Cable Sensors; Reinforced Concrete (RC) Structures; Signal Loss

Document Type

Article - Conference proceedings

Document Version


File Type





© 2004 SPIE -- The International Society for Optical Engineering, All rights reserved.