Transillumination of the subsurface, method of cavity detection and detection configuration

摘要

In a method for generating a transillumination signal of a section of the subsurface, an HPEM radiation source radiates an electromagnetic pulse into the section for the purpose of exciting electromagnetically reactive structures to emit an electromagnetic response signal. For the pulse, a pulse duration of at most 500 ns, a center frequency in the range between 10 MHz and 10 GHz, and a bandwidth in the range from 10% to 150% of the center frequency is set. The transillumination signal is formed as the sum of response signals received at a measuring location. In a method for detecting a cavity in the subsurface, the above method is carried out, and the structures are detected from the transillumination signal with the aid of a detection method, and the cavity is detected if the structures satisfy a detection criterion.