Research On RF Charging Technology For Wireless Sensor Networks

In the wireless sensor network power supply technology,the existing chemical energy power supply is limited due to the limited battery capacity,which restricts the sensor network information processing and data transmission rate;However,in the radio energy transmission technology,the mainstream magnetic resonance type radio can be transmitted,the transmission distance is short,can only achieve one-to-one charging.In order to solve the above problems,this paper designed the energy collection antenna and energy conditioning circuit,developed an efficient directional energy collection module,and proposed a one-to-many charging path planning strategy based on density and energy transmission distance to improve the charging efficiency of the sensor network.The main work is as follows:1)An efficient dual-frequency directional energy collection module is designed.The module is divided into two parts: dual-frequency PIFA energy harvesting antenna and dual-frequency energy conditioning circuit.The energy harvesting antenna combines the advantages of the strong directional performance of the quasi-Yagi antenna with the small size and simple structure of the PIFA antenna by setting three directional radiation patches arranged according to the distribution pattern of the Yagi antenna.Compared with the spiral antenna in a single frequency band,the maximum directional gain is increased by24.3%.Compared with the PIFA antenna with rectangular radiation patch,the half-power mainlobe width is reduced by 11.47% and the maximum gain is increased by 3.6%.Aiming at the 920 MHz and 2.48 GHz dual-band signals obtained from the antenna,a dual-band energy conditioning circuit is designed,which enables the antenna to achieve a long-distance power supply of two meters under the condition that the 40 W RF source provides a voltage of 3.5V to the load.2)A one-to-many charging path planning strategy is proposed from two aspects of the selection of charging stopping position and the moving path of charging device.By introducing density parameters and the energy collection radius of sensor nodes,the SEP clustering algorithm was improved to realize the selection of charging stopping position of the non-uniformly distributed sensor network.Then,the charging path planning of mobile charging device was completed by using ant colony algorithm.Through MATLAB simulation,the mobile charging path planning of random distribution points within the range of 20 ×20m2 is completed under the condition of mobile charging with 40 W power supply.Compared with the single-point charging method,this one-to-many charging strategy improves the charging efficiency by 18.64%.