On multiport antennas for MIMO-systems

A very promising method to enlarge the radio channels capacity is the use of MIMO (Multiple Input Multiple Output) systems. The need to deploy more than one antenna leads to the problem of the restricted available space reserved for the antennas, especially on the terminals. Another fundamental problem is the evaluation of the MIMO performance in a realistic propagation environment. Only a global view will bring up a realistic picture about the improvements using multiple antenna technologies. At the beginning of the presentation basics on MIMO-technology will be given. The second part will show in a very fundamental way the realisation of a compact 4-port antenna, which provides a sufficient decoupling between the ports. Finally the system performance of this antenna is investigated. Based on the analysis of the diagram correlation coefficient and the mutual coupling of the elements a basic idea of the antenna performance is evaluated. Measured and simulated correlation coefficients of typical channel matrixes taking the antenna into account will give finally an idea of the real MIMO performance.