Research On UAV And Its Array RCS Reduction Technology

Unmanned Aerial Vehicle(UAV)has been widely applied in the military field nowadays.In recent years,with the increasing demand for air defense forces in the World Military Power,which promotes the research and development of UAV.As a result,it is important to reduce the Radar Cross Section(RCS)of UAV to improve the stealth ability.Collaborative work of multiple UAVs is necessary for more complicated mission and higher efficiency.The RCS of the UAVs increases significantly when the size of the UAVs increases.It is extremely vulnerable to the threat from the enemy radar.Therefore,it has always been a problem about reducing RCS of UAVs that researchers pay close attention to.This thesis mainly studies on RCS reduction of the single UAV and UAVs,the main research work of this thesis is briefly summarized as follows:1.This thesis proposes a method for gap-loading RCS reduction of single UAV based on the characteristic mode theory.Firstly,the scattering characteristic modes of the UAV are obtained by using the theory of characteristic mode.The scattering characteristic modes with large modal weighting coefficient values are found according to the curves of modal weighting coefficients,and then characteristic current distribution diagrams corresponding these modes are obtained.The scattering characteristic modes is suppressed by slotting in the strong current position,so that the RCS of UAV is reduced.The results show that this method can reduce the RCS of single UAV successfully in a certain bandwidth.2.A method for RCS reduction of UAV is proposed when it is irradiated to plane waves in any horizontal direction.Firstly,the scattering characteristic modes of UAV under different plane wave directions are discussed by using characteristic mode theory,and the RCS of UAV is reduced by gap-loading.Finally,the RCS of UAV is reduced in multiple plane wave directions by slotting.3.Due to significant increase of RCS when multiple UAVs working in collaboration,this thesis proposes a method of reducing the RCS based on array pattern synthesis for UAVs.Besides,this thesis conducts respective researches on the RCS for one-dimensional UAV arrays and two-dimensional UAV arrays.Firstly,it computes the scattering field data for single UAV with different situations.Secondly,it calculates the RCS for UAVs based on the scattering data of each UAV combined with the array pattern function.Finally,the multi-objective evolutionary algorithms based on decomposition is applied to optimize the arrangement of the UAVs and the situation of each UAV.It realized the reduction of the RCS of UAVs in the specific visual range.