On the integration of MIMO systems into handheld devices

This work shows that it is possible to integrate several antennas into small hand-held devices to setup MIMO systems for mobile communications. The integration of three and four Inverted-F antennas into a small housing is presented. These integrated antenna arrays are analyzed by simulations of complete MIMO systems. The simulations are verified by measurements. Different quality measures for antenna arrays like the mean effective gain and for MIMO systems like the correlation properties of the channel matrix are investigated. It is shown, that a low correlation among the elements of the channel matrix can easily be obtained, even for very small antenna spacings. But realizing antenna arrays with a high efficiency, which is essential for mobile devices, is difficult The influence of a user, who holds the small device nearby the head, is also investigated. The user mainly influences the efficiency of the arrays, whereas the correlation properties remain unchanged.