| With the rapid development of science and technology,communication technology has made great progress.In particular,the rise of Internet of Things technology has made communication no longer confined to people,and the connection between people and things,things and things has become more and more close.The core of IoT technology is wireless sensing technology,and how to power many wireless sensors and other wireless devices has become a difficult problem.The idea of using solar cells or using object vibration to generate electrical energy to power wireless devices has been proposed,but these power supply methods require specific conditions and cannot be used in all applications[1].Wireless energy transfer technology solves this problem well.The electrical energy is emitted into the air as electromagnetic waves by the transmitting device,and then the wireless device supplies itself with electromagnetic wave energy in the air of the radio frequency energy harvesting system.The wireless energy transmission system mainly includes the following parts:transmitting antenna,receiving antenna,matching circuit,and rectifier circuit.The specific design contents are listed as follows:1.Based on the theoretical analysis of the antenna,a dual-frequency coplanar waveguide antenna is designed The antenna frequency is 2.45GHz and 5.8GHz,which is used to receive the electromagnetic waves emitted by the transmitting antenna.By optimizing the antenna structure to obtain the required frequency points and good matching,the simulation and measurement results are consistent.2.1n order to improve the electromagnetic energy received by the receiving antenna and improve the final efficiency of the wireless energy transfer system,a double-layer metal circular aperture open resonant ring structure is designed to excite the magnetic polarization resonance.Through reasonable design and optimization,the antenna gain can be improved by ultra-strong transmission of electromagnetic waves in a specific frequency range.3.The design of the rectifier circuit will directly determine the output voltage and the conversion efficiency.In order to output a higher voltage as much as possible,a voltage doubler rectifier circuit is adopted.This thesis uses the Advanced Design System(ADS)to optimize the voltage multiplier circuit of different orders,and finally adopts a second-order voltage doubler rectifier circuit.In order to avoid the energy loss caused by the impedance mismatch between the antenna and the rectifier circuit,a matching circuit is inserted between the antenna and the rectifier circuit to adjust the impedance.By optimizing the rectifier circuit and the matching circuit,an efficient dual-frequency rectifying circuit working at 2.45GHz/5.8GHz was finally designed.The simulation and test results of the final system show that,at OdBm input power point,the output voltage is 2.2V in the 2.45GHz band,the rectification efficiency is 48%,the output voltage is 1.3 V in the 5.8GHz band,and the rectification efficiency is 15%.This design can be used as an alternative to wireless energy transfer systems. |
