A Two-Port Chassis-Mode MIMO Antenna

The design of multiple-input-multiple-output (MIMO) antennas based on characteristic modes has attracted considerable attention recently. This letter presents a novel MIMO antenna that excites the same two eigenmodes from each of its two ports, but with a 180^° phase difference between the modal excitation coefficients of one of the dominant modes. This provides the antenna with two orthogonal radiation patterns that can be independently excited from each of the two ports of the antenna, without a complex power dividing network that is typical of other designs based on characteristic modes. A fabricated prototype gives 21.2 dB of isolation between the ports. Good agreement is observed between the measured and simulated radiation patterns, and the envelope correlation coefficient between the patterns was measured to be 0.0638.