Fabric-Based Absorber for Wearable RF Wireless Energy Harvesting

In this article, a fabric-based absorber for harvesting radio frequency (RF) wireless energy is proposed for wearable applications. The present absorber is comprised of periodic grooved bow-tie dipole arrays, fabric substrate and copper cloth ground. The copper cloth is utilized to produce periodic grooved bow-tie dipole arrays by laser cutting according to the pre-customized pattern. Then, the cutting-transfer method is utilized to transfer periodic copper cloth onto fabric substrate to integrate absorbing arrays consisting of 5 × 5 unit cells. Each unit cell comprises two pairs of grooved bow-tie dipoles. In addition, the unit cells of absorber are linked with a through channel to reduce power losses as well as transmit and gather the obtained energy from each column. Simulation results show that the proposed absorber can absorb more than 90% of the available energy at two resonant frequencies. Moreover, the rectifying circuit is set up and constantly improved, which could achieve the RF-dc efficiency of 56.6% and 40.4% at two resonant frequencies of the presented absorber. Finally, the fabric-based absorber integrated with rectifier circuit is fabricated and the measured dc voltage is 0.449V, which will hold promising applications for powering low-power wearable electronics.