Automatic Restriction of Radiated Power in 5G Handsets based on Proximity Detection to Comply with Exposure Limits

Several strategies for limiting the radiated power in 5G handsets to meet regulatory limits are surveyed, with focus on an approach wherein the proximity of a human is sensed through built-in power measurements of the handset's transmitted signal and its reflections. The measurement system is based on directional couplers and power detectors that are placed in the transmission paths leading to the device's multiple antennas. The employment of such strategy is intended to ensure that the transmitted power is restricted only when there appears to be a human at risk, while otherwise allowing unrestricted transmission power and uncompromised up-link performance.