16-Elements Helical Antenna System Integration with a Solar Cell Powered IoT Collector

An 868MHz-915MHz 16-elements helical wire antenna array design with a solar-cell integration is presented. Each element is designed to be omni-directional with the corresponding tuning stubs and ground substrate. This is shared with distributed solar cell array, powering 16- Internet of Things (IoT) transceivers operating at multiple Industrial Scientific and Medical (ISM) bands. 370mm×400mm design including the antennas, solar cells, and the tuning stubs can generate 8-watts solar power under direct sun, charging Lithium batteries. 1.6-mm thick planner design with horizontal radiation pattern resulted in average −15dB return loss at 868-MHz without using any external matching elements.