Research Of Photovoltaic Panel Antenna In Hybrid Energy Harvesting System

With the vigorous development of the Internet of Things(Io T),wireless sensor networks,as one of the core contents of the Internet of Things,have quickly become a current research hotspot.There are tens of thousands of nodes in the Io T.At present,most sensor nodes in the Io T are still powered by batteries,which will lead to node failure when the battery is exhausted.It is difficult and costly to replace batteries manually.Therefore,the continuous supply of energy has become an urgent problem restricting the development of the Io T.Because the average power consumption of sensor nodes in the Io T is less than 10 m W,the environmental energy harvesting technology is used to efficiently solve the problem of power supply for wireless sensor nodes.The output power of single energy collection is often too low and unstable,which is easy to cause intermittent output power,which is not enough to support the power supply system of the equipment.Therefore,it is very necessary to design a hybrid energy harvesting system.This thesis introduces the photovoltaic RF energy harvesting system,goes deep into the research of photovoltaic panel integrated RF energy harvesting antenna and the design of low-power input rectifier circuit to realize efficient energy harvesting system and meet the requirement of energy self-sustaining sensor nodes in the Io T.1.Aiming at the uncertainty of radiation source direction in the environment,a photovoltaic panel integrated reconfigurable antenna is proposed.The impedance bandwidth of the antenna is 24% and the maximum gain is 9.5d Bi.As the periodic superstrate of the antenna,the photovoltaic panel is placed on the upper layer of the slot antenna to make it uncovered.By mechanically moving the substrate to realize the altering of the main beam,a photovoltaic panel integrated reconfigurable antenna is designed.The photovoltaic periodic superstrate is used to broaden the bandwidth and improve the gain of the antenna.Its side-fire radiation and flexible beam can meet the requirements of photovoltaic panel alignment with the sun and beam alignment with the surrounding high-power radiation source.The coupling feeding mode makes the RF energy harvesting circuit and solar energy harvesting circuit independent of each other,avoiding the design of additional isolation structure.The relative bandwidth of the antenna is 25%,and the maximum gain reaches 10.5d Bi.2.Further,aiming at the problem of multiple power sources in space,a photovoltaic panel integrated multi-beam antenna is designed to effectively increase the energy receiving range.The maximum radiation direction of the antenna is 30° and-30°,the gain is greater than 9d Bi,and the impedance bandwidth is 25%.3.A photovoltaic panel integrated Yagi antenna is proposed to solve the problem of hybrid collection of RF energy and solar energy from long-distance radiation sources.Based on the traditional microstrip Yagi antenna,by increasing the number of photovoltaic panel structure as parasitic units to expand the utilization area of photovoltaic panel and improve the collection capacity of solar energy.The impedance bandwidth of the antenna is 33% and the maximum gain is 9.5d Bi.4.Finally,Due to the low RF energy density in the environment,a low-power broadband rectifier circuit with a center frequency of 2.5GHz is designed.Measured result indicates that when the input power is-10 d Bm,the maximum rectification efficiency is 43%,and the frequency range of rectification efficiency above 20% is 2.34-2.67 GHz.It has the characteristics of low power and broadband rectification.Aiming at the power supply problem of sensor nodes in the Io T,this thesis adopts the photovoltaic RF energy collection method to realize the self-power supply problem of Internet of things nodes.With the comprehensive consideration of the material,shape,light receiving area of the photovoltaic panel and its integration with the antenna,antenna radiation direction and aperture direction,the photovoltaic panel integrated reconfigurable antenna,photovoltaic panel integrated dual beam antenna,photovoltaic panel integrated Yagi antenna and low-power broadband rectifier circuit are designed.Finally,the feasibility and reliability of the hybrid energy collection system are proved through the overall test of the system.