Optimal placement of MIMO antenna pairs with different quality factors in smart-phone platforms

In this contribution, an investigation on the use of tunable antennas for a compact implementation of multi input multi output (MIMO) phones has been done. The position of the exciting elements has been investigated as well as the antenna´s bandwidth impact on the mutual coupling. It has been show that generally narrow band antennas have increased inherent isolation and in some special cases they can have impressive levels of isolation. A two by two MIMO system has been considered and the influence of the user has not been investigated. A design for a compact MIMO tunable antenna is proposed with good performance without the increased complexity of a decoupling technique.