Research On Wide Coverage Radio Frequency Energy Harvesting Technolog

In recent years,in order to meet the energy supply needs of electronic devices and microsystems in the Internet of Things,RF energy harvesting technology has attracted widespread attention due to its unique advantages.As the core part of the RF energy harvesting system,the rectenna has the role of energy reception and energy conversion,and its design is directly related to the working performance of the entire system.How to receive more energy and improve energy conversion efficiency in a limited power density environment is the main direction of current rectenna research.In the actual RF energy harvesting process,the frequency band,coverage,polarization mode and power merging scheme of the receiving antenna will affect the energy receiving capacity of the system.In this thesis,according to the needs of different RF energy harvesting scenarios,a broadband and dual-polarized omnidirectional rectenna arrays are designed to reduce power loss,and the solutions suitable for wide-coverage RF energy harvesting applications are explored.The main work of this thesis includes:1.A broadband vertically polarized omnidirectional rectenna array is designed,with a working frequency of 2.25 GHz～3.6 GHz.In the receiving antenna design part,an omnidirectional antenna array was realized by circumferentially arranging eight slotted Vivaldi antenna elements.In the rectifying circuit design part,on the basis of the traditional half-wave rectifying circuit,the multi-branch parallel connection structure is used to effectively expand the working bandwidth of the rectifying circuit,and the efficiency is higher than 60% in the relative bandwidth range of 82.8%.DC power merging is used to integrate the output power of each element in the broadband omnidirectional antenna array.Through simulation and measurement,the RF energy harvesting performance of the rectenna array at multi-frequency points in the working frequency band and omnidirectional reception is verified and analyzed.2.Three dual-polarized omnidirectional rectenna arrays with different power merging schemes are designed,all of which operate at 2.45 GHz.In the receiving antenna design part,two omnidirectional antenna arrays are used to receive horizontally polarized electromagnetic waves,and four-dipole arrays are used to receive vertically polarized incoming waves.By optimally combining the two-part sub-antenna arrays,a dual-polarized omnidirectional antenna array can be realized.In the rectifying circuit design part,the half-wave rectifying structure is used to convert RF energy to DC energy.Different RF power merging networks are designed to combine antennas and rectifying circuits,and three rectenna arrays based on different power merging principles are obtained.Based on the simulated and measured results,the RF energy harvesting performance of the three rectenna arrays at different polarizations and omnidirectional reception is analyzed and studied.