A mode-based technique for compact linear MIMO arrays

Summary form only given, as follows. A practical technique for building compact linear antenna arrays based on orthogonal radiation is presented. This approach utilizes passive couplers to separate out different orthogonal eigenmodes of linear arrays with closely-spaced elements as individual radiation mechanisms. In this way, undesired effects due to mutual coupling and spatial correlations can be avoided. Consequently, MIMO radio front-ends can be made very compact in size by using arrays with closely-spaced elements.