PROBLEM TO BE SOLVED: To accurately specify dielectric constant on a ground surface, even in an area where vegetation, or the like, exist. SOLUTION: A Brewster-angle specifying unit 32 specifies an incident angle, at a position of the bottom of a recess in a line drawn by plotting and interpolating a signal intensity of a reflected waves relative to the radio waves of vertical polarization radiated to an observation object for each incident angle, as the Brewster angle of the of the observation object. Because the Brewster angle varies with the dielectric constant of the observation object, a dielectric constant specifying part 33 specifies the dielectric constant of the observation object, on the basis of the specified Brewster angle. COPYRIGHT: (C)2011,JPO&INPIT
