Importance

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Abstract

An electromagnetic signal having originally the time variation of a rectangular pulse is transmitted into a medium with conductivity .sigma.. It is distorted by the medium to a signal f(.sigma.,d,t) if it traveled the distance d from a transmitter to a scattering or reflecting object and the same distance d back to the transmitter. The time variation f(.sigma.,d,t) of the distorted signal can be calculated for any conductivity .sigma. and distance d. Using the conductivity .sigma. known from previous measurements, the returned, distorted signal f(t) is compared with computed distorted signals f(.sigma.,d,t) for various distances d. The computed signal f(.sigma.,d,t) that is most similar to the actually received signal f(t) determines the distance d to the scattering or reflecting object. The comparison between the computed, distorted signals and the actually received signal is done by cross-correlations. The peak amplitude or the energy of the received signal becomes unimportant if cross-correlation is used, which means the physical size or radar cross-section of the scattering or reflecting object becomes unimportant.

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First Claim