A Decoupling Network Based on Characteristic Port Modes

In this paper, we present a novel decoupling network for coupled antenna systems using characteristic port modes. Specifically, we observe that the the port response of a multi-port antenna is the superposition of the characteristic modal responses, while the superposition relation for multi-port antennas can be represented as a transformer bank. By developing a transformer network that inverts the superposition relation, we realize a decoupling network for the coupled multi-port antennas. Depending on the antenna's property, this decoupling network could be a broadband, e.g. for symmetric networks, or a narrow-band realization.