Characteristic Mode Analysis of ESPAR for Single-RF MIMO Systems

A systematic method based on the Theory of Characteristic Modes (TCM) for finding orthogonal radiation patterns any electronically steerable parasitic array radiator (ESPAR) is described. This can be useful designing single-RF front-end multiple-input multiple-output (MIMO) systems in which utilized as a basis set space modulation (SM) or full multiplexed MIMO systems. The $N$ -port formulation TCM and not restricted to antenna type configuration. It also provide closed formed solutions element currents required generate patterns. In addition an approach load reactances ESPAR generating provided quasi-Newton utilizing form expression initial approximate solution. Approximate estimation effective aerial degrees freedom ESPARs discussed. Two simulation examples ESPARs, 4-element linear dipole 8-element rectangular planar inverted-F array, using SM well are provided, demonstrating effectiveness proposed method.