Research On Clutter Suppression For Airborne Three-Dimensional Array

Modern warfare have a growing demand for stealth capability,aerodynamic performance and target detection capability of airborne radar.The three-dimensional antenna airborne radar conformal to the fuselage has a smaller bearing load,a smaller radar cross section,better aerodynamic characteristics and a larger scanning range compared to conventional airborne radar with planar array antenna.Therefore,it is of great significance to carry out the research on clutter suppression for airborne three-dimensional array.Aiming at the complex problem of the clutter characteristic caused by the multi-surface structure of the three-dimensional array antenna,a uniform clutter model of array with universality is established,which provides conditions for realizing the more accurate description of clutter characteristics of three-dimensional heterogeneous array.In terms of the space-time clutter suppression of airborne radar with three-dimensional array,the array reconstruction method based on the correlation coefficient matrix?the space-time reconstruction method based on clutter space-time equivalent?the space-time data interpolation algorithm and other array reconstruction methods are proposed to realize the adaptive array reconstruction of variable array structure and element number for the problem of clutter decorrelation and platform motion.Aiming at the problem that the full space-time adaptive processing technology is difficult to realize due to the large number of three-dimensional array element,a reduced-dimension processing algorithm based on generalized multi-order decomposition of spatial domain is proposed,which reduces computational complexity and improves clutter suppression performance in the case of a small number of samples by spatial dimensionality reduction.The work of this thesis is outlined as follows:1.The clutter model of airborne three-dimensional array is established.Different from the traditional planar array clutter model,the model fully considers the polarization characteristics of element and clutter,which is a uniform clutter model of array with universality,and it can realize the more accurate description of clutter characteristics of three-dimensional heterogeneous array and provide clutter model and clutter characteristic support for subsequent clutter suppression methods.2.The research on airborne three-dimensional array reconstruction method is carried out.Aiming at the problem of clutter decorrelation caused by the long baseline and the disaffinity of polarization characteristic of the three-dimensional array and the problem of independent and identical distributed samples restriction,an array reconstruction method based on the correlation coefficient matrix is proposed,which improves the clutter correlation by a better choice of array elements and obtaines the optimal clutter suppression performance by the three-dimensional array reconstruction method under the condition of satisfying the clutter correlation and the number of available samples.Aiming at the problem of the sidelobe performance degradation of receiving pattern caused by the stereoscopic structure of the three-dimensional array,a space-time reconstruction method based on clutter space-time equivalent is proposed,which can effectivity improve the clutter suppression performance when the platform speed meets the DPCA condition.In order to deal with the imperfect condition of platform speed instability,a space-time data interpolation algorithm is proposed,which makes the clutter cancellation performance better by using the characteristic of data phase consistency.Through the simulation experiments of various array reconstruction methods,the validity of the proposed method is verified.3.The research on reduced-dimension processing algorithm based on generalized multi-order decomposition of spatial domain is carried out.Taking into account the large number of three-dimensional array element,the proposed method decomposes the spatial steering vector into generalized tensor product of two low-dimensional vectors after dimensionality reduction in the temporal domain,correspondingly,it transforms the calculation of the adaptive steering vector into the generalized multi-order decomposition,which effectivity improves the clutter suppression performance without affecting the spatial degree of freedom while reducing the calculation and the number of samples required.