FPGA-Controlled Polarization-and Frequency-Reconfigurable Antennas

The main research contents of this paper are reconfigurable antennas.Reconfigurable antennas have attracted extensive attention in academic and industrial circles in recent years because they can be dynamically adjusted according to system requirements and surrounding environment to improve their frequency or radiation characteristics.So,it can improve spectrum utilization and reduction of energy attenuation due to multipath effects.In general,typical parameters that a reconfigurable antenna can be reconfigured are frequency,polarization,radiation patterns or a combination of the three.Because reconfigurable antennas have more versatile functional choices than traditional antennas,reconfigurable antennas will have broad development space and application prospects.Firstly,the basic principle of antenna radiation is expounded,and the knowledge of inner field,radiation field and pattern of circular microstrip antenna is analyzed in detail,which lays the theoretical foundation of the whole paper.The microwave components used in the development of reconfigurable antennas are described immediately afterwards,which means working principle of reconfigurable antennas can be better understood.Finally,the basic knowledge and design flow of the FPGA are described,which provides a better platform for the combination of the antenna and the FPGA.Secondly,based on the existing reconfigurable antenna with four linear polarization states,it has been modified to have seven linear polarization states in four polarization directions.The concept of antenna polarization and its reproducibility have been elaborated.At the same time,in order to realize the programmable control of the reconfigurable antenna,the method of using FPGA to control the antenna is proposed,and the working principle and programming idea of the FPGA are described in detail.Finally,the FPGA-controlled reconfigurable antenna is placed in a microwave dark room for measurement,and the seven polarization states can be measured at one time under the control of the FPGA.Finally,a polarization-and frequency-reconfigurable antenna has been designed.The antenna is a two-layer structure and each layer consists of a center circle and sixteen sector areas.At the same time,the antenna design process and various parameter analysis are introduced in detail in the paper.Ten polarization states of ten frequencies can be achieved through different open combinations.In order to improve the degree of integration of the entire system,a connection board between the antenna and the FPGA was specifically designed.In order to verify the performance of the antenna is also measured in the microwave dark room,to achieve a better measurement results.