A Compact Source-Load Agnostic Flexible Rectenna Topology for IoT Devices

This article presents a new compact lightweight radio frequency (RF) energy harvesting system. The system relies on a dual-tapered transmission line-based matching network that stretches the rectification capability of an integrated Schottky diode. This topology is demonstrated on a 2.4 GHz rigid harvesting system with a resulting power conversion efficiency that reaches up to 58% over 0 dBm input RF power. Its performance is compared with a reference rectifier that relies on a typical open circuit shunt-stub matching network. The rectifier along with a miniaturized monopole antenna is then tailored for a flexible substrate with a resulting efficiency around 50% at 0 dBm input power. The rectifier exhibits an almost flat efficiency over the 2.3-2.5 GHz frequency span despite wide load variations. The system is characterized in multiple bent configurations featuring high and stable performance. It is demonstrated that for different bent states, the proposed flexible harvester does not display large variations in harvested power. Thus, the presented rectenna demonstrates the remarkable combination of compactness, flexibility, and stability. Equipped with these features, such rectifier can be plugged into a variety of sensors, even on wearable surfaces, which makes it ideal for Internet of Things (IoT) applications.