| Microwave Power Transmission（MPT）has broad application prospects in solving energy problems and Internet of Things technology.As the key part of the MPT system,the rectenna is mainly composed of a receiving antenna and a rectifier circuit.The main principle is that the microwave energy in the space is received by the antenna,and then the microwave energy is converted into DC energy output through the rectifier circuit.This article focuses on two key technologies:the design of the receiving antenna in the rectenna and the design of the rectifier circuit.On the basis of full investigation of relevant research at home and abroad,the main research contents of this article are as follows:（1）Regarding the rectifier circuit,fully study the design methods and design principle of the rectifier circuit.A comparative analysis of the characteristics of different rectifier structures and rectifier diodes is carried out.On this basis,a single-frequency rectifier circuit working at 2.45GHz and a dual-frequency rectifier circuit working at 2.45GHz and 5.8GHz are designed respectively.The circuit design includes the design of the output filter and the design of the matching network.Through the overall circuit simulation after adding the output filter and the matching network,the single-frequency rectifier circuit achieves a maximum efficiency of 78%,and the dual-frequency rectifier circuit achieves a maximum efficiency of 73.76%and 74.1%at 2.45GHz and 5.8GHz.In order to verify the actual effect of the circuit,the two circuits were processed and tested in kind.The test results show that the single-frequency circuit achieves a maximum efficiency of 73.44%,and the dual-frequency rectifier circuit achieves a maximum efficiency of 67.65%and 66.79%.（2）A circularly polarized harmonic suppression antenna that works at 2.45GHz is designed.The circular polarization and harmonic suppression characteristics of the antenna are realized by loading dual-coupled line and meandering slots.The simulation results show that the antenna suppresses the second and third harmonics of the operating frequency,and the antenna axial ratio is close to 0.1d B.In order to verify the actual effect of the antenna,the actual antenna was processed and tested.The measured results show that the antenna has the best axial ratio close to 0.1d B at 2.295GHz,the 3d B axial ratio bandwidth exceeds 30Mhz,and the antenna’s radiation characteristics and harmonic suppression characteristics are basically consistent with the simulation results.（3）Using the method of loading short studs and meandering slots,a dual-frequency antenna working at 2.45GHz and 5.8GHz was designed,and the antenna’s actual measurement and simulation results were compared.The measured results show that the S11 of the antenna at 2.3GHz and 5.6GHz are-30.84d B and-24.06d B,and the gain at 2.3GHz and 5.6GHz are2.57d B and 7.1d B.The curve trend of the test result is basically consistent with the simulation result. |
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