Modeling And Simulation Of HRWS SAR Based On Elevation Frequency Scanning

Compared with traditional radar,synthetic aperture radar(SAR)can provide more target information and has been widely used in military and civilian detection and monitoring fields.The swath and resolution of the imaging scene are two important performance indicators in imaging.The wide swath can achieve simultaneous irradiation of large range-scenes.The obtained data is highly time-effective.The high resolution can obtain rich scene target information,which affects the performance of the final SAR image.Traditional imaging modes such as spotlight mode and scanning mode cannot achieve high-resolution wide-band imaging at the same time.The existing high resolution wide swath imaging modes mainly rely on spatial filtering to achieve deblurring,which can reduce or avoid the contradiction between azimuth resolution and range-swath.However,as the requirements for resolution and swath bandwidth continue to increase,the number of channels required for high resolution wide swath imaging modes that rely on spatial filtering to defuzzify will increase accordingly,which limits the improvement of imaging performance.Therefore,it becomes more meaningful to study a new high-resolution wide-swath imaging system.The content of this paper is to use the elevation frequency scanning array to achieve high-resolution wideswath imaging.Then,the new characteristics of the echo signals of the elevation frequency scanning array will be analyzed.Finally,the applicable imaging algorithm will be derived.The main work of this article includes:1?The transmit pattern of the circulating coding array is studied and the expression of the instantaneous beam pointing angle of the synthesized pattern is given.In order to accurately control the beam pointing angle of the synthetic pattern,the principle of stationary phase is used to solve the synthetic pattern.Therefore,the problem of solving the instantaneous beam pointing angle is converted into a function zero solution problem.The data simulation was used to verify the characteristics of the pattern,which provided the basis for the subsequent control beam scanning in the wide swath.2?The signal model of elevation frequency scanning SAR is studied and the waveform design guidelines of elevation frequency scanning SAR are proposed.In order to solve the problem of range ambiguity in elevation frequency scanning SAR,design and calculate the parameters of the transmitted signal and circulating coding array to control the instantaneous beam pointing angle and range of intra-pulse beam scanning by analyzing the given ground swath,range ambiguity component isolation requirements and range resolution index.Therefore,the fuzzy components of different distances in the swath are isolated in different distance frequency bands and the frequency domain filtering can be used to replace the spatial domain filtering.3 ? The imaging algorithm is studied and an imaging algorithm suitable for elevation frequency scanning SAR is proposed.Based on the ground echo model,the spectral expression of the echo is derived.In order to reduce the influence of frequency shift caused by intra-pulse frequency scanning on the range and azimuth focusing process in the echo spectrum,the distance dimension processing function needs to be adjusted based on the CS imaging algorithm.The instantaneous frequency is calculated by the instantaneous beam pointing angle of the synthesized pattern of elevation frequency scanning array and the distance band-pass filter is designed to suppress the range ambiguity.Through data simulation verification,the proposed algorithm can achieve high-resolution wide-swath imaging.