Compact MIMO-arrays based on polarisation-diversity

The application of MIMO (multiple input multiple output) systems in small handheld devices is difficult, since usually large antenna spacings are required to obtain uncorrelated channel coefficients. This paper shows, using dipoles, that a combination of pattern- and polarisation diversity yields uncorrelated channel coefficients that can be exploited by MIMO system. A way of modeling the impact of antennas on MIMO systems is presented here. The complex radiation pattern, polarisation, mutual coupling of the antennas and cross polarisation coupling within the transmission channel are taken into account. It is shown that a combination of polarisation and pattern diversity leads to very compact antenna arrays, that still yield uncorrelated channels.