Power Density Measurement at 5G Millimeter-Wave Using Inverse Source Method

5G user equipment, such as mobile terminals and tablets shall comply with radio frequency (RF) safety guidelines. At millimeter-wave frequencies, human exposure to RF electromagnetic fields (EMFs) is evaluated in terms of incident power density, i.e., free space Poynting vector. As, the electrical size of mobile terminals increase with higher frequencies, longer testing times are needed to determine power densities in the proximity of devices by traditional scanning. A new approach to accurately determine the power densities in close vicinity to a device is based on standard near-field measurements and processing by the inverse source method. This method is faster, simpler, and thus desirable compared to dedicated scan on a device dependent surface. The new method use the capabilities of the equivalent current expansion to determine the power density by NF/NF transformation on any surface and at any distances according to the safety normative. The method was presented on a device in [7] by comparison to simulated power densities. Although correlations were promising, some discrepancies were likely due to the approximated numerical model of the device. In this paper, the SH4000, Dual Ridge Horn, with well-known full wave model is investigated to validate the power density determination against accurate simulations.