A Compact Orthogonal-Mode Decoupling Network for Metal-Rimmed MIMO Antennas

A high-isolated dual-antenna pair based on orthogonal-mode excitations is presented for mainstream metalrimmed smartphones in this article. The decoupling of the dualantenna pair can be achieved by integrating two antenna units in the same radiator and feeding it with a modified directional coupler. The antenna will excite the orthogonal dipole and monopole modes when two external ports are fed separately. With this decoupling scheme, the dual-antenna pair shows an isolation of more than 15 dB, and the reflection coefficients are below -8 dB in 3.4-3.6 GHz. In addition, we optimize the size of the feeding coupler to make the overall structure smaller, which is in line with the trend of antenna miniaturization.