On small terminal MIMO antenna correlation optimization adopting characteristic mode theory

This work proposes a MIMO antenna system for mobile terminals, based on a compact form factor and packaging implementation, with a very low magnitude of the complex correlation coefficient and an impressive isolation. An isolation better than 20 dB has been achieved using a folded monopole and a commonly adopted PIFA (planar inverted F antenna) on a platform with a very small form factor (100×50 mm). The proposed implementation is based in the application of the characteristic mode theory to obtain orthogonal radiation modes. The adopted topology enables uncorrelated antenna system at 750 MHz, while maintaining high total efficiency and adequate gain imbalance. In this present paper simulation model as well as prototype measurement results are presented, demonstrating the implementation feasibility of such antenna system in compact mobile device embodiment.