Eigenmodal feed based decoupling network for two ports MIMO and diversity

A decoupling network based on the excitation of the orthogonal patterns of the chassis wavemodes is presented. The coupling to the chassis wavemodes is mainly depends on the coupling element shape and position on the chassis. A two coupling element are optimized and placed on the short ends of 100mm×40mm chassis where the odd and even modes of the chassis major axis are strongly coupled. A modal feed network is presented to excite the odd and even chassis modes with their corresponding eigenvectors. The presented modal feed network provides an isolation of more than 20 dB between the two ports antenna system. External matching circuit is designed to match each of the chassis wavemodes impedance to the 50 ohm.