More than 20 antenna elements in future mobile phones, threat or opportunity?

This paper discusses the issues in antenna design for future mobile communications terminals caused by the addition of more and more antennas into the devices. There can be more than 10 different radios in the terminal and some of them will utilise adaptive antenna systems with more than 5 antennas. Thus it is possible that a future terminal device will have more than 20 antennas. This can be either a threat or an opportunity depending on the viewpoint of e.g. a terminal manufacturer or an antenna manufacturer, respectively. The challenges connected to the large number of antennas are the volume required by the antennas in a small terminal, coupling between the antennas and finding locations for the antennas where user interaction is low. The possible solutions include minimisation of the size of antenna elements, re-use of the same antennas in many systems, and methods to isolate the antenna elements from each others.