Tunable MIMO antenna for small handsets

In today´s wireless communication systems, the need for more frequency bands and higher data rates provides challenges for designing compact, efficient, and environment-insensitive handset antennas. One way of obtaining this is by using frequency-reconfigurable Multiple-Input Multiple-Output (MIMO) antennas to both minimise the antenna volume and to compensate for user-originated impedance detuning losses. The current work contributes to describing the challenges or issues that have to be taken into account when designing well-performing frequency-tunable MIMO antennas. Obtaining this goal requires co-design of both the antenna and the tuning circuit used. An example antenna design is used to illustrate the different aspects of this work. The design features independently frequency-reconfigurable antenna elements that are able to cover most of the LTE-A bands. The performance of the example design in terms of antenna volume, bandwidth, and efficiency makes it a viable candidate for practical tunable MIMO implementations.