A method for azimuthal sidelobe suppression in mimo-sar near-field measurements
A MIMO-SAR and azimuth sidelobe technology is applied in the field of MIMO-SAR near-field measurement imaging azimuth sidelobe suppression, which can solve problems such as poor image sidelobe suppression, meet the technical requirements of engineering applications, and improve The effect of range and strong adaptability
Active Publication Date: 2017-05-10
BEIHANG UNIV
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[0063] The technical problem to be solved by the present invention is: the present invention aims at the problem that the traditional windowing method is not effective in suppressing the image side lobe in the azimuth direction (horizontal distance dimension) during MIMO-SAR near-field imaging, and proposes an image side lobe A new method of suppression processing, which uses convex optimization technology to solve the optimal weighting coefficient of each channel in the MIMO-SAR azimuth direction, and uses the obtained weight to weight the data of each channel before imaging processing, which solves the problem of MIMO-SAR near Field imaging azimuth side lobe suppression, greatly improving the image dynamic range of MIMO-SAR near-field imaging
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[0097] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.
[0098] The present invention provides a method for MIMO-SAR near-field measurement imaging azimuth sidelobe suppression, specifically:
[0099] 1. MIMO-SAR-FBP imaging algorithm
[0100] Assuming that the MIMO array is a linear array composed of M transmitting elements and N receiving elements, the coordinates of the mth transmitting element are X Tm , the coordinate of the nth receiving element is X Rn , the center of the array is the coordinate origin. The polar radius of the scattering center σ(R,θ) in the radar coordinate system is R, and the polar angle is θ, such as figure 2 shown.
[0101] The distance from the mth transmitting array element to the scattering center is The distance from the nth receiving element to the scattering center is m∈[1,2,…,M], n∈[1,2,…,N].
[0102] Echo model of the signal:
[0103]
[0104] Image ...
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The invention discloses a method for MIMO (multi-input multi-output)-SAR (synthetic aperture radar) near field measurement imaging azimuth side lobe suppression. According to the method, the azimuth side lobe suppression is realized through each channel data weighing, and in order to obtain the optimized side lobe suppression effect, the optimum channel weight vector W<opt> needs to be found. The W<opt> solution process is as follows: firstly, echo data with the channel weight w is decomposed in the azimuth focusing process, and an azimuth point diffusion function expression B=Aw is obtained; secondly, the value of the ideal point diffusion function at the main lobe part is 1, the value at the side lobe part is 0, the solution of the vector w is converted into a mathematical optimization problem; finally, a mathematical optimization algorithm-convex optimization algorithm is adopted for solving to obtain the optimum channel weight vector W<opt>, and the effect is the best when the optimum channel weight value is used for azimuth side lobe suppression. The method can be used for solving uniform linear array, and can also be used for the side lobe suppression of the interstitial deletion array element linear array, and is also applicable to the side lobe suppression in linear guide rail scanning SAR imaging and the like.
Description
technical field [0001] The invention relates to the fields of communication, microwave imaging, signal processing, and MIMO (Multi-Input Multi-Output) theory and mathematical optimization problem solving, in particular to a method for sidelobe suppression in MIMO-SAR near-field measurement imaging azimuth. Background technique [0002] Existing imaging measurement radars for electromagnetic scattering diagnosis of low detectable targets mainly include inverse synthetic aperture radar (ISAR) using turntable rotating target measurement and synthetic aperture radar (SAR) imaging system using linear guideway mechanical scanning measurement. For the diagnostic measurement of the scattering characteristics of real low detectable targets, ISAR imaging needs to build a special target turntable and support system, through the mechanical rotation of the turntable to synthesize the imaging aperture, to achieve azimuth high-resolution imaging measurement of the target [References 1-3] L...
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IPC IPC(8): G01S13/90
CPCG01S7/2813G01S13/9017G01S13/9056
Inventor 刘永泽许小剑
Owner BEIHANG UNIV