Spatial Averaging Calculations of 5G Beam-Forming Antennas for EMF Compliance Assessments

When calculating whole-body spatially averaged electromagnetic field (EMF) exposure at cellular base stations utilizing massive multiple-input multiple-output (MIMO) and beam-forming technologies, the typical approach is to use the maximum gain envelope of all horizontal and vertical steering directions of the traffic beam. When considering the vertical steering capability of the antenna, calculations performed from multiple vertical beam directions at maximum gain across the spatial averaging range will result in an overconservative assessment since the traffic beams are not directed at multiple directions simultaneously with the same effective isotropic radiated power (EIRP). A more accurate approach would be to differentiate between multiple vertical tilt steering directions. By calculating the whole-body spatially averaged EMF exposure for each individual tilt or vertical steering direction, a less overly conservative compliance boundary for the beam-forming antenna may be derived.