This project focuses on the design of efficient multi-antennas for mobile terminals at frequency bands below 1 GHz. This is because at such frequencies, existing designs typically result in two or more antennas strongly interacting with the chassis, leading to strong coupling among the antennas and poor antenna performance. To overcome this problem, a rigorous approach will be used to understand the fundamental electrical properties of the chassis, and how small changes on the chassis structure influence these properties. The antennas will then be designed to exploit these properties, such that the chassis enhances, rather than degrades, multi-antenna performance. Furthermore, the design approach will be extended to account for the impact of user on the antenna-chassis interaction, so to mitigate possible performance impact. The project will deliver a new multi-antenna design approach that will give significant performance gains over current designs, which directly benefits Swedish industry. Moreover, it will provide new insights into the underlying operating mechanism of terminal antennas, which are of great interest to both antenna researchers and engineers.