A hybrid energy supply system based on metamaterial antenna integrated solar cells for IoT nodes

Abstract

In this paper, a hybrid energy supply system based on solar cells integrated metamaterial (MTM) antenna is presented for use in Internet of Things (IoT) nodes. The work develops an energy supply system having dimensions of 40×40 mm2, that is qualified for storing and releasing energy. To realize miniaturization technique and gain enhancing, the design of antenna employs complementary split-ring resonator (CSRR) and a 4×1 array. Meanwhile, this work is miniaturized by integrating solar cells on the substrate. The result is a very compact integrated antenna with overall dimensions of 82.5×33 mm2 and the ability to harvest radio frequency (RF) energy and solar energy, which covers frequency band from 5.2 to 6.2 GHz. Different antenna structures were built to analyze S11 spectra, voltage standing wave ratio (VSWR), radiation patterns and surface current distribution, respectively. For further verification, the design was fabricated and compared to the simulated one. Moreover, practical experiments were conducted with four kinds of environment setup. The fabricated antenna provides maximum voltage of 1.63 V, indicating a good applicability to RF energy harvesting. The energy supply system provides a stable output voltage with 2.9 V in different conditions. The results highlight the feasibility of energy supply system in energy harvesting and powering for various IoT nodes.