Research On Multi-Input Multi-Output Radar System Based On Stepped-Frequency-Continuous-Wave

Inspired by the multi-input multi-output array technology in the field of communication,a new radar system,multi-input multi-output array radar,has emerged.At the same time,it has become a research hotspot in the field of radar because of its high work efficiency.Multi-input multi-output array radar systems have various forms.Broadly speaking,as long as the design concept of multi-channel input and output is satisfied,it can be regarded as multi-input multi-output radar system.In recent years,the switched MIMO array radar based on the idea of "time division multiplexing" has been widely studied because of its relatively simple technology,low cost and strong spatial data sampling ability.This paper designs a new type of ultra-wideband Vivaldi antenna for the formation of time-division multi-input multi-output array radar,which combines the advantages of ultra-wideband and step-frequency continuous wave signals to improve the utilization of radar antenna,optimize the penetration ability and detection resolution of the system.Ability and detection resolution have obtained effective experimental results in the study of sounding and wall penetration imaging.Among them,the research of wall penetration imaging is of great significance to the application fields of hostage rescue,security inspection and geological disaster rescue.The research contents of this paper are summarized here.First,in the context of participating in the cooperative research of multi-input multi-output radar technology in the Engineering Geophysics Laboratory,a new ultra-wideband Vivaldi antenna is designed through slotted miniaturization technology to improve the penetration ability and resolution of the radar array.Considering the balance and optimization of the antenna's low-frequency characteristics and size miniaturization,it meets the requirements of portability and high-resolution imaging of the multi-input multi-output array radar system.The structure size of the antenna is 250 mm × 200 mm × 1.6 mm and the operable frequency band of S11 less than-10 db is 0.5-2.5GHz.Secondly,the principle of MIMO array radar is studied in detail.The vector network analyzer(VNA)is used as the signal transmitter of radar system to provide stepped frequency signal;the small GaAs RF switch switches the receiving and transmitting antenna to improve the system controllability and data acquisition speed.It provides support for the following research of radar through wall imaging algorithm.Then,imaging research and experiments are carried out around the suppression of wall clutter in through wall imaging.The back projection algorithm is combined with Hamming window filter and Time gating to carry out two-dimensional through wall experimental imaging.It can suppress the wall reflection clutter and optimize the imaging effect.High resolution two-dimensional through wall imaging of metal dihedral angle and human body target is realized.At the same time,the experimental results also directly verify the actual working effect of the designed Vivaldi antenna.The designed Vivaldi antenna can assist the radar system to obtain good resolution and penetration ability.Finally,the inverse time migration algorithm based on the finite difference is applied to the system through the wall imaging,which is divided into four steps: preprocessing,wall parameter inversion,target coarse positioning and inverse time migration imaging.It is found that this processing algorithm is completely effective for the forward single target imaging,which lays the foundation for the improvement of the subsequent through the wall imaging algorithm and the improvement of imaging accuracy.Taken together,the array radar system constructed by the antenna designed in this paper and the imaging methods studied has been successfully applied in the imaging detection of multi-input multi-output array radar.