Well-established solutions capable of scanning electromagnetic fields in anechoic environments essentially rely on the massive use of absorbers, in order to keep under check energy scattered by the metallic parts of an automatic positioning system. Solutions of this kind are convenient whenever the field to scan is the result of line-of-sight (LOS) propagation. In complex media, where multi-path propagation imply non-LOS contributions, the introduction of absorbing materials can irremediably alter the behavior of the medium under test and therefore the field to be scanned. In this case, a field scanner rather needs to be as transparent as possible. This paper introduces the main ideas behind an alternative automatic positioning system designed in order to ensure a low perturbation of the response of a medium. The impact of the scanner is assessed when used in a reverberation chamber with a varying degree of reverberation, in order to emulate the conditions found in realistic complex media. Expected applications are mainly found in sounding propagation in complex media.