Adaptive Basis Patterns Computation for Electronically Steerable Passive Array Radiator Antennas

Single-RF front-end MIMO systems have drawn the attention of the research community due to their considerable advantages against the conventional MIMO systems. MIMO multiplexing capabilities are implemented in the beamspace domain using parasitic antenna arrays with one active and many parasitic elements, like the Electronically Steerable Passive Array Radiator (ESPAR) antenna. The multiplexing is achieved in terms of linear combination of diverse symbols with orthonormal basis patterns. Initially, an analytical method was proposed to derive the basis patterns, which remain orthogonal in rich scattering environments. Recently, the numerical calculation of channel-aware orthonormal patterns was introduced. In this paper, we extend the presented method in 3-dimensional channels and radiation patterns. The proposed technique is based on the singular value decomposition of the wireless channel, as seen in the beamspace domain, and it adaptively computes 3D orthonormal basis patterns at both transmitter and receiver sides. It is expected that the 3D analysis will facilitate the compensation of the body effects in the handheld terminal performance.