Multi-port ladder impedance matching for compact MIMO communication systems

We investigate multi-port ladder impedance matching (MLM) for enhancing the capacity of compact MIMO communication systems. MLM builds upon single-port matching (SPM) techniques by incorporating an additional reactance that connects adjacent antenna ports together and promises enhanced performance while maintaining good bandwidth. We demonstrate numerically for a 5-element compact MIMO system that optimum MLM can increase capacity by up to 9% compared to SPM. In addition we also show that over wide bandwidths MLM performs better than SPM.