Recovering handset diversity and MIMO capacity with polarization-agile antennas

Design guidance is provided for multiple-input-multiple- output (MIMO) antenna systems on handsets-a strong prospect for next generation wireless devices. Handheld wireless devices are likely to be rotated out of their optimal polarization, thereby experiencing significant power losses. An existing polarization-agile antenna design and a novel four-spoke extension recover significant fractions of the rotation-induced losses both in switched-antenna diversity and capacity calculations-all but 1 dB of diversity gains at a 99% system reliability, half of the CΕ losses or 80% of the Cο,1 losses. These gains benefit four- and ten-element arrays and remain significant in the presence of 6 dB cross coupling and in volume-restricted arrays. Diversity order investigations also demonstrate a new, non-Rayleigh locus of curves describing patch antennas subject to rotation.