Recovering handset MIMO capacity with polarization-agile antennas

Multiple Input Multiple Output (MIMO) communication systems rely on significant variation between multiple signal paths to create independent channels for communication. Transceiver signal strength to or from a portable handset is subject to large variations due to the "essentially random orientation" typical of their use [1] and the resultant polarization mismatch between the handset antenna and the impinging wavefronts. This work synthesizes an inexpensive solution to recover a significant fraction of these average capacity losses. Marrying the idea of antenna subset selection [2] and polarization agile antennas [3], one arrives at a polarization-selectable approach of great value both to MIMO systems and to single-input single-output (SISO) systems. This work demonstrates that the typical assumption of a receiver with fixed orientation is very inaccurate for predicting the capacity of handheld MIMO wireless devices. It corrects the standard MIMO normalization with the more appropriate reference array normalization for antenna comparisons. It demonstrates significant recovery of the capacity and diversity losses from parallel array element designs through switchable polarization-agile elements.