Multiband MIMO antenna arrays

This paper considers the implementation of multiple element antenna arrays for MIMO wireless systems for use with multiple wireless standards operating at different frequencies. The capacity of such systems for a realistic channel model is considered, and it is shown that it is not generally worthwhile to reduce element spacing below 0.4 wavelengths, and proposes an array topology using a mixture of multi-band and single band elements to maximise the benefit of MIMO while minimising the hardware requirements. Some examples of multi-band elements are given.