Effect of element radiation patterns on the capacity of MIMO system

The concept of MIMO (multiple-input multiple-output) has been for some time a topic of interest in the research community, since multiple antenna transmission allows a significant increase in the capacity of communication systems without requiring an increase in bandwidth or transmitting power. In this promising area there has been much attention given to system aspects such as space-time coding and decoding and channel modeling another vital area is the MIMO antenna arrays themselves. Currently, there are some major challenges, such as reducing the size of the array for small handsets while reducing the correlation between antenna elements. In this paper, we will discuss the effect of element radiation pattern in the antenna array on MIMO capacity. Both omni-directional and directive antennas are considered to provide a fair comparison, and furthermore, a specific type of antenna known as ´half-bowtie´ is implemented in an array, being measured and simulated in given channel scenarios. The results illustrate that the more pattern diverse the elements are, the higher the mean capacity is, but also with the larger variance.