Antenna Design For UWB Through-The-Wall Radar

In recent years,with the rapid development of science and technology,radar plays an increasingly important role in various applications.It was first applied to prevent ship collision in the sea and detect without barrier in the air,and then gradually extended to the requirements of penetrating walls or detecting the ground,such as counter-terrorism and disaster relief.The performance requirements of Radar system are also getting higher and higher,and through-wall radar(TWR)is one of the important applications.The impulse system wall-penetrating radar has many advantages such as strong penetrability,high resolution and strong anti-interference performance.As an important part of radar system,the performance of antenna has great influence on the whole system.The main design content of this paper is to develop an antenna applied to ultra-wideband wallpenetrating radar,which can be specifically divided into the following parts:First of all,the background and significance of this study are briefly introduced,the development status at home and abroad is understood by consulting the literature,the working principle of the through wall radar system is introduced,the relationship between the attenuation of electromagnetic wave and the wall material is studied,the waveform and frequency spectrum of the pulse signal are analyzed based on the expression of Gaussian function,and the main working frequency band of the through wall radar antenna is determined.According to the above information,Vivaldi antenna and microstrip antenna are finally determined as the research objectives of this paper.Then,it briefly introduces the development of Vivaldi antenna and some related basic theories,including the types of Vivaldi antenna,surface current distribution,radiation characteristics and so on.Based on the theoretical analysis,a series of Vivaldi antennas are designed.By comparing with each other,the vertical slotted Vivaldi antenna with the size of 116.6mm × 100 mm × 1.6mm is selected.The simulation analysis and time-domain performance analysis of this antenna are carried out.The results show that the performance of the surface antenna is good in time-domain and has a certain practical value.Finally,since Vivaldi antenna is a linearly polarized antenna,a circularly polarized microstrip antenna is designed.Firstly,some basic theories of microstrip antenna are introduced,including the analysis method,classification,characteristics and feeding mode.Based on theoretical analysis,coplanar waveguide feed structure and multivariate method are selected for antenna design.The antenna size is 100 mm × 100 mm × 1.6 mm,standing wave ratio bandwidth is 0.92-3.88 GHz,and axial ratio bandwidth is 1.11-1.38 GHz.The simulation analysis and time domain performance analysis of the UWB circularly polarized microstrip antenna fed by coplanar waveguide show that the performance of the surface antenna is good in time domain and has certain practical value.