Direct evidence and implications of Brewster's angle damping observed by synthetic aperture radar images

This paper describes the direct evidence of Brewster's angle damping and its effects on polarimetric analyses observed in the synthetic aperture radar (SAR) images of concrete constructions such as seawalls. The reflectivity of concrete material is nearly zero at the Brewster angle for X-band VV-polarization microwave. The TerraSAR-X image acquired over the Tokyo Bay, Japan at small incidence angles showed strong double-bounce reflection by the sea and construction surfaces with HH-polarization, while with VV-polarization, very little radar backscatter was observed. The same effect was seen in the images of concrete walls on ground, and a swamp area covered by reeds. This effect is illustrated with HH/VV intensity and phase difference images, and ground survey data; its implication is also suggested for better understanding of polarimetric SAR images.