Design of multi-antenna systems for UMTS mobile phones

In this paper, we focus on multiple antenna-systems for portable UMTS devices. First, we perform a state-of-the art review of the best solutions developed all around the world. Then, we present all the UMTS multi-antenna systems designed at the LEAT of the University of Nice-Sophia Antipolis since 2004. We especially describe the neutralization technique dedicated to enhance the total efficiency of several radiators integrated within the same (small) ground plane. Lastly we try to identify promising solutions and future trends in this area.