Simultaneous multiport matching circuit optimization for multiantenna systems

Matching circuit design for multiantenna systems is getting increasingly complex due to the increasing number of antennas and the explosion the number of communication bands. In this paper we discuss the optimization criteria of matching circuits for multiantenna systems. It is shown that in many cases the matching circuits for different antenna ports cannot be optimized separately, because due to the antenna coupling a change in the matching of one port will affect the matching of all other ports. For multiantenna systems the goal of matching should be to get the best possible efficiency for each antenna port. This goal differs from e.g. filter matching where the goal is to get the best possible energy transfer between the external ports, which is typically equivalent to having a good impedance match at the external ports simultaneously.