Design Of Microstrip Antenna Array For RF Energy Harvesting

With the rapid development of electronic information technology,numbers of micro low-power wireless sensors have been widely used.Traditional power supply for wireless sensors is wired or battery power,resulting in circuit complexity and unsustainable problems,which is a big challenge for power supply of wireless sensors.By harvesting energy from electromagnetic wave or solar energy or thermal energy,and converting them into usable energy is a new way for the self-powered of wireless sensors,which is called the energy harvesting technology.Because of its no restrictions on time and environment,RF energy harvesting technology is becoming a hot research in recent years.In this paper,harvesting energy from WIFI and 4G communication system are concerned,and the research of microstrip collecting antenna array and rectifying boosting circuit is finished,followed by experimental verification.Work of this paper is mainly from the following aspects.First,as the front-end of RF energy harvesting system,antenna determines the maximum power and efficiency.In this paper,the study of the process and critical technology of antenna design have been done,including how to calculate the size of the microstrip antenna array and the feeding network and how to realize circular polarization.Second,for the harvesting of widely distributed WIFI and 4G wireless signal,three kinds of antenna array are designed and simulated by using HFSS software,which includes an antenna array of 2x2 turncated circular polarized working on 2.45 GHz,an antenna array of 1x4 linear polarized working on 2.45 GHz,and an antenna array of 2x2 dual polarized working on 2.6GHz.Third,for different frequency of RF energy harvesting,two different boost rectifier circuits working on 2.45 GHz and 2.6GHz have been designed.In the process,fourth order boost rectifier circuit were designed.And the matching network were designed according to different frequency and different input power by way of electromagnetic simulation software ADS,and the calculation and simulation were done,which showed that the largest efficiency of 77% can be reached.Fourth,a platform for testing the system of RF energy has been setup including a network analyzer,a signal analyzer,a RF signal source and an anechoic chamber.The RF energy harvesting systems working on two different frequencies were tested on the platform.The testing result showed that a circularly polarized and dual polarized antenna array can improve the power of RF energy harvesting system,and harvest WIFI and 4G signal energy efficiently,and the largest efficiency of 41% can be realized.