This article introduces a measurement methodology for the evaluation of the specific absorption rate (SAR) of a class of multiple-input and multiple-output (MIMO) communication devices. It is dedicated to the specific MIMO systems in which the relative phases between the antennas are rapidly changing and in very courteous durations, as implemented using the STBC (Space-Time Block Code) function. Indeed, a particular and new subject in these measurements arises when we consider the SAR systems that use vector field measurements, and exploiting the principles of field equivalence for the reconstruction of the field distribution in the volume from samples of a subset of the time-independent harmonic-field that is induced in the internal media simulating the human body.
This article presents measurement methodologies to address this new case of transmissions as well as to contribute to the development of standards of the International Electrotechnical Commission (IEC) harmonizing the procedures for measuring the exposure to electromagnetic radiation, while taking advantage of SAR measurement systems that are based on vector and radiofrequency measurement of the electromagnetic fields.