Research On Circular Imaging Algorithm Of Millimeter Wave Radar

Synthetic Aperture Radar(SAR)through formation of Synthetic Aperture Radar carrier movement,breakthrough the limitation of the real aperture radar for antenna length.SAR’s traditional way of working for the linear model,but the linear model of radar has a small field of view and the azimuth resolution is easy to be limited.Circular Synthetic Aperture Radar(Circular SAR)can make up for the deficiency of the linear model of radar,and Circular SAR can achieve all-round observation target even a 360-degree observation,compared with the linear model of radar.Circular SAR observation is wider,higher resolution and can provide more accurate target information.Millimeter wave radar has low cost,small size,light weight,high spatial resolution,strong ability to penetrate fog,smoke,dust,not affected by bad weather,and can work all day and all day.In recent years is widely used in civilian areas.In this paper,77 GHz millimeter wave radar combined with Circular SAR is used to promote the application of ground imaging.The existing Circular SAR imaging algorithms have the problem that the imaging accuracy decreases and the computational efficiency decreases with the enlargement of the scene due to the oblique distance approximation.This paper presents a new algorithm for Circular SAR imaging,which can solve the shortcomings of traditional algorithms.This paper focuses on the following aspects:Firstly,the basic theoretical knowledge of Circular SAR imaging is introduced,which is illustrated from three aspects: azimuth and range resolution analysis,point target response analysis,and geometric model of Circular SAR system.The derivation process of echo signal is described in detail,and the characteristics of echo signal are analyzed.The specific index of target response of analysis point is introduced to measure the imaging result.Secondly,Back Projection(BP)imaging algorithm and Range-Doppler(RD)imaging algorithm used in Circular SAR imaging are introduced,and the imaging principles,imaging steps,algorithm computation and existing problems of the two algorithms are described in detail.Finally,according to the spherical wave sign of echo signal.A Polar Coordinate Format imaging algorithm based on spherical wave decomposition is proposed.The algorithm does not need to approximate the slant distance,which greatly improves the efficiency of the algorithm.Moreover,the algorithm does not need to consider the number of grid points,which improves the efficiency of the algorithm.The imaging algorithm in this paper is compared with BP and RD algorithms by simulation experiments,and the effectiveness of the proposed algorithm is further verified by actual experiments.