A Planar Orbicular Rectenna Array System With 3-D Uniform Coverage for Wireless Powering of IoT Nodes

Microwave power transfer (MPT) is a revolutionary technique for charging batteries of wireless sensor nodes in smart applications. However, sensor nodes can be positioned at any arbitrary orientation and location with respect to the microwave transmitter (Tx). Therefore, harvested DC power depends on the node's position and orientation. Thus, to reduce this reliance, a novel, fully integrated planar multisector rectenna (Rx) array is designed to achieve a nearly uniform 3-D spherical DC coverage. To realize orientation insensitive azimuth and elevation plane coverage, the proposed Rx features eight radially arranged endfire Rx (EFR-antenna) elements, and a bore-sight Rx (BSR-antenna) element with multiarms for inherent DC combining is used at the center with orthogonally polarized ports. Furthermore, direct conjugate matching of antenna and rectifier circuit with integrated operation is applied to realize a fully integrated design. This reduces insertion losses and achieves the desired 3-D coverage along with miniaturization, shaping it suitable for deployment at space-constrained IoT sensor nodes for orientation oblivion wireless powering.