A Slot Antenna Array With Low Mutual Coupling for Use on Small Mobile Terminals

In order to take full advantage of the benefits to be obtained by using MIMO techniques for mobile communications, it is necessary to use an antenna array which is both compact and also has low mutual coupling between ports. Generally these requirements are conflicting and to achieve them simultaneously is the subject of much research. In this paper a novel design for a two element cavity backed slot (CBS) array is described which has a measured mutual coupling of less than -15 dB despite an element spacing of only lambda/6. This is achieved by adding a simple and easily manufactured meandering trombone structure to an existing CBS array which carries a portion of the input signal to the feed of the neighboring element. Measured and simulated results are presented for the behavior of the antenna and predictions are presented for the achievable channel capacity in several realistic scenarios.