Coupling Between Multipath Environments Through a Large Aperture

A key issue in measuring the shielding of buildings against wireless communications signals is presented. We use a mode-stirred reverberation chamber (RC) to emulate the EM coupling through windows or doors. This is achieved experimentally by leaving the RC door open. The room hosting the RC is identified as an external semi-reverberant space, and thus used to generate the stochastic field exciting the internal RC through the door opening. Two methods for the transmission parameter measurement and shielding effectiveness estimation are compared: the first one consists in moving receiving antenna within a volume, the second one makes use of a rotating stirrer. The comparison confirms the interchangeability of the two techniques provided a proper averaging factor is introduced. This argument supports a quasi-ergodic hypothesis in imperfect and semi-open reverberating environments. The measured aperture SE is compared to a theoretical value given by an ideal reverberating environment.