Test Reduction for Power Density Emitted by Handset mmWave Antenna Arrays

The exposure to electromagnetic field (EMF) from phased antenna arrays integrated into wireless devices operating at the millimeter-wave (mmWave) part of the spectrum should be evaluated in terms of power density (PD). Two aspects related to test reduction when evaluating the radiation from handset antenna arrays are considered. First, the peak PD decay with the distance from 4-elements antenna arrays is analyzed. The focus is on finding the size of the volume around the handset beyond which the PD is so low that its measurement can be omitted. By limiting the measurements to the inside of the exposed volume, the total test time is reduced. Antenna configurations that are representative for current trends in handset technology are chosen: arrays of half-wavelength dipoles and patches operating at 26 GHz, 28 GHz, and 39 GHz, and having inter-element spacing either 0.5λ or 0.9λ. The second investigation aims to determine the critical distance between two 4-elements phased arrays for which the peak PD when the two arrays operate simultaneously is similar to the peak PD when only one array operates at the time. The study shows the configurations for which the number of tests can be reduced while having sufficiently accurate results.