Composite Structural Design of Fabric Substrate to Improve the RF Energy Harvesting Performance of Wearable Antenna

Radio frequency energy harvesting based on a flexible antenna is widely used in powering wearable electronic devices, while the antenna is sensitive to the influence of the human body. The composite structural design of fabric substrate through introducing an artificial magnetic conductor (AMC) has been adopted to minimize the impact of the human body in the design of a wearable fabric-based antenna for energy harvesting. The simulated and measured antenna performance with and without the AMC on the human body has been conducted to validate the role of the AMC. The results showed that the multilayer composite structure of the fabric substrate successfully minimizes the influence of the human body on the antenna for energy harvesting. The maximum transmission distance of the optimally designed fabric-based antenna increases to 218 cm, while the power conversion efficiency (PCE) of the antenna with the AMC on the human chest is 43.5%, restored to the original 88.3%. Moreover, the simulated results showed that the antenna gain and forward radiation performance backed with an AMC improved dramatically with the antenna on the human chest. These results indicate that the integration of an AMC with a fabric-based antenna enhances the antenna energy harvesting performance and isolates the effect of the human body. It can be concluded that a multilayer composite structure of a fabric-based antenna substrate by backing an AMC is feasible for wireless radio frequency energy harvesting.