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 Conference 2004 -- Sensors and Smarth Structures Techonologies for Civil, Mechanical, and Aerospace Systems (2004: Mar. 14-18, San Diego, CA)


Electrical and Computer Engineering

Second Department

Civil, Architectural and Environmental Engineering

Keywords and Phrases

Cathode Ray Oscilloscopes; Cracks; Dielectric Losses; Electric Potential; Optical Resolving Power; Reinforced Concrete; Coaxial Crack Sensors; Multiple Signal Reflections; Spatial Resolution; Sensors; Sensitivity; Signal Loss; Skin Effect

International Standard Serial Number (ISSN)


Document Type

Article - Conference proceedings

Document Version


File Type





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

Publication Date

18 Mar 2004