Averaging time required for measuring the specific absorption rate of a MIMO transmitter

This paper presents a new method to measure electric field (E-field) for human-body exposure to electromagnetic fields from Multi-Input Multi-Output (MIMO) wireless communication transmitters, and an estimation of averaging time required in the E-field measurement. The proposed method is to measure time-averaged E-field, and the averaging time is the duration required for a measurement system to make averaged E-field converged. The estimation is based on averaging the square of amplitude of received signals or measured E-field strength. Several simulation results with different measurement parameters for MIMO wireless communication transmitters are presented and discussed. It is pointed out that the averaging time in E-field measurements for multi-antenna transmitters is considerably longer than that for single antenna transmitters.