Research On Application Mode And Signal Processing Method Of Arc Array Radar

Arc array synthetic aperture radar(SAR)is a new kind of microwave imaging system for wide area observation.When the system is applied to the helicopter platform,it can realize short revisiting time and full azimuth imaging around the platform.In order to give full play to the potential and efficiency of arc array radar,it is necessary to explore and study the application mode of arc array radar.Bistatic synthetic aperture radar(Bi-SAR)is a kind of SAR system with separate transmitter and receiver,which has the advantages of decent concealment,strong anti-jamming ability and flexible system design.Three-dimensional SAR(3D-SAR)imaging can obtain the threedimensional information of the scene target,which can more intuitively and accurately describe the three-dimensional observation scene information.This paper focuses on the bistatic and 3D imaging application mode of arc array SAR.The main research contents are as follows:1.A bistatic arc array SAR imaging model with one fixed station is established,the signal model of this mode is derived,the spatial resolution is also analyzed,and an imaging algorithm suitable for the model is proposed according to different flight states of helicopter.Aiming at the problem of range cell migration in bistatic arc array SAR imaging in high altitude cruise flight of helicopter,an arc array SAR imaging method based on keystone transform is proposed.The method uses keystone transform in frequency domain to eliminate the coupling term between array angle and range time,and solves the problem of range migration in range Doppler domain.Aiming at the problem that the far-field approximation method will bring some big errors when helicopter landing,a bistatic arc array SAR imaging processing method based on implicit function derivative method is proposed,which regards the stationary phase point as an implicit function of Doppler frequency,and solves the stationary phase point by algebraic operation after deriving the implicit function equation,Then,the twodimensional spectrum of bistatic arc array SAR is derived by using stationary phase principle.The effectiveness of the above imaging method is verified by computer simulation.2.A 3D imaging model of airborne forward arc array SAR is established,the signal model of this mode is derived,the three-dimensional resolution is also analyzed,and a3 D imaging algorithm suitable for the model is studied.Based on the original twodimensional arc array SAR technology,the 3D information is obtained by helicopter platform forward motion.Firstly,the 2D SAR images obtained from helicopter forward flight are arranged along along-track direction,then the range-along-track echo data are intercepted along each cross-track direction,and sequentially perform imaging processing.The three-dimensional imaging of the whole forward-looking scene is realized through two imaging steps: range-cross-track imaging and range-along-track imaging.Finally,the effectiveness of this imaging method is verified by point target simulation.