Removal of undesired wavefields related to the casing of a microwave scanner

This paper deals with the scattered field data measured by a closed microwave scanner and discusses the removal of the effects of the metal casing as a preprocessing step before actual inversion of the data can take place. It is shown that Rayleigh's reciprocity theorem furnishes a relation between the scattered field data obtained in the closed microwave scanner and the scattered field data as if they were obtained by an open scanner without the metal casing. This relation leads to a system of linear equations, from which the desired scattered field data with respect to the equivalent open scanner are obtained.