2021 年 57 巻 4 号 p. 227-236
For a safety diagnosis of RC structures, a microwave radar method has advantages on a nondestructive inner inspection. In this report, novel processing techniques for the microwave radar to improve an inspection accuracy on a buried object survey has been proposed. Specifically, precise and accurate estimation techniques for a propagation time and a reflection phase shift have been considered, based on the time-frequency analysis methods. Also, in order to improve an accuracy of a back projection on a migration process, the improved microwave propagation path model in which an air layer and a substrate layer are newly including has been proposed. Performances of the propagation time and the reflection phase shift estimation method have been confirmed experimentally. Additionally, theoretical propagation times derived from the proposed propagation path model have corresponded to an experimental one well, and validities of proposed both techniques have been shown.