Study And Design Of Through-The-Wall Radar Antenna

With the development of today's society,there is a higher demand for the detection performance of radar systems in urban anti-terrorism,disaster relief,and military.The through-wall radar system can detect and locate the target position after non-electromagnetic transparent medium such as building or wall,which has high application value and prospect.The pulse width of the impulse pulse is extremely narrow and the spectrum is extremely wide,so it is not easy to be intercepted,and the anti-interference ability is strong,which can greatly improve the detection probability of the stealth target.The impulse system radar system has high resolution and good wear.Permeability has become one of the preferred technologies for wall penetration detection.The choice of antenna plays an extremely important role in the performance of the system,directly affecting the results of the detection.The main work and contents of this thesis are as follows,focusing on the design of the wall-mounted radar antenna with better performance such as miniaturization and broadband.Firstly,this thesis briefly analyzes the research background and practical application value of the through-wall radar system,and investigates the development history and current situation of the through-wall radar system at home and abroad.Based on Fourier transform,the waveform spectrum of Gaussian pulse signal is analyzed.According to the actual requirements of high-peak and narrow-pulse pulse signal source development and system volume requirements,the operating frequency band of radar system is determined to be 0.3~0.8GHz and 0.8~3GHz.The comparative analysis of common ultra-wideband antennas,Vivaldi antennas and dish antennas were selected as research,and the research and design work of through-wall radar antennas was carried out accordingly.For the high frequency band,based on the design theory of Vivaldi antenna,the degree of miniaturization of the antenna is improved by resistance loading,and the antenna is structurally loaded to improve the low frequency gain and bandwidth of the antenna.The improved Vivaldi antenna has an impedance bandwidth of 0.484~3.403 GHz and an antenna size of 72 mm ? 104 mm ? 1mm.The simulation and measured results show that the antenna has good working performance and certain practical value.For the low frequency band,the scheme selected in this thesis is a butterfly antenna,which is combined with an elliptical patch and a dish antenna which also have broadband characteristics.In order to make the through-wall radar antenna system more convenient,the loaded antenna is miniaturized by the arm.Load resistors at the end of the antenna,open a semi-circular groove to eliminate current reflection caused by the arm,and improve the impedance bandwidth.According to the theory of circular polarization,the orthogonal butterfly antenna is directional radiation by the reflection cavity,and the circular polarization and circular polarization performance are studied by the broadband Wilkinson power divider.The working frequency band of the final circularly polarized through-wall radar dish antenna is 0.205~1.07 GHz,which satisfies the engineering design index of 0.3~0.8GHz.The overall size of the antenna is 220mm? 220mm? 50 mm.The simulation results and experimental measurements show that the designed circularly polarized butterfly antenna has compact structure and good performance,which can meet the requirements of the application of the through-wall radar system.