Water detection in thermal insulating materials by high resolution imaging with holographic radar

The present research is aimed at the application of high resolution holographic images for the detection and characterization of low water content (0.2–1 g) water patches in insulating materials. The images acquired with manual scanning with high frequency (7 GHz) holographic radar with I / Q outputs are compared with a high speed electromechanical scanner with 4 GHz holographic radar. Small patches of the order of 22 mm  ×  22 mm buried at 18 mm into insulating materials with a low dielectric constant, have been accurately reconstructed with the high frequency holographic radar but they can also be detected with the lower frequency holographic radar at even greater depths. (paper)