Design and Optimisation of a 2.4 GHz Radio-Frequency Energy Harvesting System for Low-Power Internet of Things (IoT) Applications

This paper presents the design and performance evaluation of a highly efficient 2.4 GHz Radio-Frequency Energy Harvesting (RF-EH) system specifically modified to meet the energy requirements of low-power Internet of Things (IoT) applications. This system incorporates a high-gain 4x4 Microstrip Patch Antenna (MPA) Array, a single-stub Matching Network (MN) and a 5-stage RF-to-DC rectifier using the Cockcroft-Walton Voltage Multiplier (CW-VM) topology. The antenna is mounted on Rogers RT5880 substrate with a thickness of 1.588 mm and a relative permittivity of 2.2, and fed by a 50-Ω microstrip feed line. The antenna was designed using Computer Simulation Technology (CST) Studio Suite 2019, while the rectifier and MN were implemented in Keysight Advanced Design System (ADS) 2022. The antenna achieved a high gain of 19.29 dBi and a directivity of 20.01 dBi, with radiation and total efficiencies exceeding 84 %. The antenna demonstrated a highly directive E-Plane radiation pattern with a narrow beamwidth of 19.4° and a side lobe level of -13.8 dB, indicating a more focused reception of RF signals and a good suppression of unwanted radiation. The rectifier achieved a peak Power Conversion Efficiency (PCE) of 89.913 % and a peak output voltage of 16.424 V at an input power of 17.5 dBm. More importantly, low-input powers ranging from -20 dBm to 0 dBm produced usable DC output voltages from 0.456 V to 4.144 V, respectively, demonstrating strong suitability for IoT applications operating under limited RF conditions. These results demonstrated the system’s potential for integration into large-scale indoor and outdoor IoT networks. The proposed system supports sustainable, maintenance-free and battery-less deployments, advancing the development of autonomous wireless systems.