Analysis And Design Optimization Of Multi-resonant Frequency And Wide Frequency Band Rectenna For Miniature Energy Harvester

With the rapid development of the Internet of Things(Io T),wireless sensor networks,biomedical implant systems,wireless charging systems,and smart buildings,a large amount of wireless sensors have been deployed.The main source of power for these wireless devices is still the battery,which increases the size of wireless devices.In addition,the battery life is limited.Also,it is expensive to replace batteries for wireless devices/sensors in some application scenarios.On the other hand,with the development and advancement of silicon microelectronics technology,the power consumption of a wireless system is getting lower and lower,reaching microwatt level.Consequently,it is possible for the system to collect energy from the surrounding environment to power itself.Therefore,the energy harvesting has become a topical issue of wireless sensor networks.Although our ambient environment has an abundant different RF sources,the power density is relatively low.In this regard,an ideal miniature energy harvester should be a multi-resonance frequency,wide-frequency band,generally called multiband,high-gain one in order to collect enough electromagnetic energy.In this point of view,the dissertation will focus on the development of a multiband,high-gain rectenna for miniature energy harvesters.First,a multi-frequency monopole rectenna is proposed.According to electromagnetic field and antenna theory,the dissertation illustrates the principle of a monopole antenna.On this basis,a monopole antenna topology of multiple L-shaped branches is proposed.And a mathematical model of electromagnetic inverse problem for the design optimization of a multi-frequency and multiband rectenna is presented.Second,an improved particle swarm optimization(PSO)algorithm is proposed to optimize the the rectenna.Particle Swarm Optimization(PSO)is a global optimization algorithm with simple concept and easy implementation.However,the shortcomings are the poor population diversity and slow convergence rate.Therefore,the improved PSO introduced Cauchy mutation operator and differential mutation operator to improve the population diversity,and tournament algorithm and elite reservation strategy to improve its global convergence ability.Then the effectiveness and advantage of the improved algorithm are verified by the analysis and calculation of typical mathematical functions.Finally,the optimal design of a four-frequency and a five-frequency monopole rectennas are realized by using the above-mentioned theory and method.In order to improve the computational accuracy,the finite element method is used to calculate the electromagnetic performance parameters.The results show that the 4-frequency and 5-frequency monopole rectennas can realize the high gain in collecting 4-frequency and 5-frequency RF energies,providing an alternative solution for the energy harvesting.Therefore,the monopole multi-frequency rectenna in this dissertation has a promising engineering application prospect.