A microwave based “wall probe” has been developed which is capable of nondestructive evaluation of architectural structures. By using microwaves in the 8 to 12 GHz range this probing instrument can detect subsurface characteristics through concrete, brick, wood or other building materials to depths in excess of 12 inches.

The instrument interrogates a structure from a single side by transmitting a microwave signal into the surface at some angle of incidence and receiving the reflected signal some distance away on the same side of the structure. The transmitted signal is partially reflected at each internal boundary of different dielectric constant, giving a composite reflection which contains information from each internal layer. The reflected composite signal is compared in phase and amplitude to the transmitted signal and that reading is considered the “signature” of the structure under test. Computer algorithms analyze the signature for recognizable features and nonstandard construction.