Wireless MIMO base station near and far field measurement challenges

Wireless communication systems use Multiple Input Multiple Output (MIMO) antenna techniques to increase coverage, data throughput and spectral efficiency. Frequently, beamforming techniques are used to provide additional antenna gain relative to Single Input Single Output (SISO) systems. Wireless devices with non-detachable antennas, the regulatory compliance must be achieved through radiated emissions tests. Radiated measurements above 1 GHz (at 3 meters' test distance) create further complications because long conductors and slots generate near-field radiation conditions beyond 3 meters. This paper examines near and far-field conditions for MIMO antennas and a transmitter systems and suggests how radiated emissions testing could be improved.