Research On Clutter Suppression For Airborne Conformal Array

As a more generalized array,the conformal array can be regarded as the extension and promotion of conventional arrays,and its elements are conformal to the surface of the carrier.The conformal array has a smaller radar cross section,better stealth and flight performance,and a larger beam scanning range.Therefore,it has a broad application prospects.The airborne conformal array radar will face strong ground clutter when detecting targets,and because its array is more complex than the traditional planar array,its clutter suppression processing is also more difficult than the traditional planar array.Therefore,it is necessary to develop the clutter suppression method for conformal arrays.In this thesis,firstly,the universal clutter echo model is established for the problem of the change of space-time characteristics of clutter caused by the arrangement of conformal array elements in three-dimensional space.Then,aiming at the range-dependency of clutter caused by conformal arrays,a compensation method based on spatial vector steering matrix is proposed.The method uses the reference unit' s main clutter center as a reference,and compensates the spatial steering vector corresponding to the main clutter center of different distance units to the main clutter center of the reference unit.Finally,aiming at the polarization loss and polarization de-correlation caused by the single-polarization array element,a method for suppressing the conformal array clutter based on the fully-polarized antenna and the non-uniformity compensation of clutter is proposed.The method uses two mutually perpendicular full-polarization elements to receive echoes,improves clutter correlation,and compensates the range-dependency of clutter through clutter compensation method,which can significantly improve the clutter suppression effect.The work of this thesis is summarized as follows:1.The pattern model and the clutter model of airborne conformal array are established.Compared with the planar array,the curved surface characteristics of the conformal array lead to different gains of the radiation patterns of the array elements in the same direction and different polarization directions.Therefore,the radiation directionality and polarization characteristics of each array element should be fully considered when establishing the pattern model and the clutter model in the space,time,and polarization domains to more accurately describe the clutter characteristics of the conformal array and create a foundation for clutter suppression in subsequent sections.2.The research on airborne conformal array clutter suppression method is carried out.Aiming at the non-uniformity of sample data caused by the clutter's range-dependency of conformal arrays,a compensation method based on spatial vector steering matrix is proposed.This method uses the reference unit's main clutter center as the reference,searching clutter block positions that are closest to the main clutter center of the reference distance unit from the position of the clutter block in all distance unit.Then,the spatial steering vector corresponding to the position of these clutter blocks is compensated to the main clutter center of the reference unit,and the compensation of the clutter's range-dependency of the conformal array airborne radar is completed.3.The research on clutter modeling and clutter suppression methods for fully polarized conformal array is carried out.Aiming at the polarization loss and polarization de-correlation caused by the use of single-polarization array elements,a conformal-array clutter suppression method based on fully-polarized antenna and clutter non-uniformity compensation is proposed.The method uses two mutually perpendicular full-polarization elements to improve the clutter echo correlation,and improves the homogeneity of the sample through the clutter non-uniformity compensation method,which can significantly improve the clutter suppression effect.Then the performances of full-polarization and single-polarization are compared,and the clutter range-dependency of the full-polarization model is compensated to further improve the clutter suppression performance.