Electromagnetic Exposure from Wireless Devices as Function of Distance

A measurement study has been conducted to understand the relationship between user exposure and distance of the wireless device to the body. This topic is pressing given the recent proposal of the European Committee for Electrotechnical Standardization (CENELEC) to perform Specific Absorption Rate (SAR) testing at 0 mm distance to the body for body-worn test conditions. Based on the two main interaction mechanisms of the coupling of the incident fields with tissue simulating media [1, 2], a monotonic increase of the induced fields with reduced distance is expected. However, early research has already shown that proximity of the user may detune the transmitter structure. This may result in a higher SAR at distances greater than 0 mm to the body. This topic deserves a thorough and comprehensive study so that a standardized testing procedure can be proposed that is both conservative and easy to implement with minimal impact on test time. The results of this study are regularly presented to relevant standards bodies.