Impact of the Elevation Scanning Angle on the Vertical Compliance Distance of 5G Massive MIMO Antennas

The evolution of mobile radio networks towards 5G leads to a deployment of massive MIMO antennas which are able to serve spatially separated users with individual beams. For site certification procedures, in Germany for instance, all base station antennas are assumed to radiate with maximum transmit power using a maximum envelope of all possible tilts and scanning angles. For the expected high scanning range in elevation, this might lead to increased vertical compliance distances.This paper evaluates the dominant factor causing the vertical compliance distance and investigates the impact of the beam scanning range for two designs of a massive MIMO antenna. The results show that the vertical compliance distance is caused by the main lobe, as long as a part of it is below the horizon. Compared to the case of no electrical downtilt, a vertical scanning range of ±15° increases the vertical compliance distance up to 161 %.