Bandwidth limitations and optimum low-band LTE MIMO antenna placement in mobile terminals using modal analysis

The upcoming LTE standard requires multi-antenna systems in hand-held devices. In recent years the advantages of modal analysis in MIMO antenna design compared to S-parameter as used for a single antenna were presented. Eigenvalue decomposition provides a powerful description of a MIMO antenna system. All basic parameters of a multi-port antenna system are explicitly defined in this paper using modal representation of antenna properties. The main tradeoff for low-band MIMO antenna systems is between the size and attainable bandwidth. Two low-band 2-port antenna arrangements are compared in terms of modal radiation quality factors as the figure of merit for bandwidth evaluation. Recommendation is given for choosing optimum antenna placement in hand-held device.