Multiport antenna systems for MIMO and diversity

Recent trend to minimize the mobile phone antenna size is to use the chassis as the main radiator especially at lower frequencies. Providing multiple antenna support for these small devices is more challenging due to large coupling between the antenna ports. However, with the help of characteristic modes of conducting bodies, it becomes possible to realize up to four port antenna systems that have acceptable return loss over 2.4 GHz ISM band and the cross-talk is less than −20 dB over the band of interest.