3d borehole radar antenna and algorithm, method and apparatus for subsurface surveys

摘要

The invention relates to a borehole radar tool comprising, in a housing (2) a transmitting antenna and a receiving antenna both of which comprise, near the housing wall (2), a dipole antenna (8) and a reflector (10) opposite thereto. Also provided are an algorithm, method and apparatus for determining electromagnetic contrast information of a site into which electromagnetic fields (27) are emitted. Signals (29) generated by induction are intercepted and, using a back-projection algorithm including a suitable weighting factor, are converted into contrast information. The algorithm and/or method can be recorded in a computer program or on a data carrier. Also disclosed is a method of determining said weighting factor. The invention further provides a method and apparatus for subsurface surveys in which electromagnetic pulse signals are emitted. All the necessary response signal samples are taken from each response signal received, and these are converted into a response signal word in order to characterize the response signal. Successive response signal words are buffered to form a data word in order to provide an image of the subsurface structure.