Focused synthetic phased array for subsurface imaging

This paper summarizes the theory and results of a focused synthetic rectangular array for microwave detection and imaging of buried objects. The proposed technique uses a bistatic antenna system with transmitter and receiver located at the angles of incidence and reflection, respectively, of the radiation illuminating the ground. Furthermore, these angles are chosen equal to the Brewster angle of the ground medium, i.e., the angle at which only radiation having its polarization perpendicular to the plane of incidence is reflected. Consequently, if the antenna polarizations are in the plane of incidence, ideally all of the radiation will be transmitted into the ground and none will be reflected. After reflection from a buried object, the radiation will again be completely transmitted from the ground to air at the Brewster angle. Although this is a geometrical optics idealization in the presence of complex scattering phenomena in a partially conducting medium, the oblique propagation geometry significantly reduces surface reflections.