耦合目标近场散射外推技术研究

Near-Far Field Extrapolation Technique for Coupling Targets

针对具有多次散射的耦合目标在不满足远场条件下测量的散射方向图发生畸变的问题,通过分析耦合目标的近场-远场转换关系,提出一种"多发多收"模式的近场散射外推方法.在获得全角域的近场双站信息后,对各角度近场接收的散射数据进行外推处理,然后根据互易定理,将外推后的数据等效为"远场发射、近场接收"数据.接下来对该数据再进行一次外推,满足"远场发射、远场接收"的条件,最后取出对角线上的元素获得各角度的远场RCS(Radar Cross Section,RCS).通过建立存在强耦合机制的二面角和腔体结构模型,利用FEKO和MATLAB软件对方法进行仿真,将"多发多收"外推的结果与远场RCS进行比对.结果表明:该方法得到的结果与远场RCS方向图吻合良好,全角域均值误差小于1dB,验证了方法的有效性.

In allusion to the problem that the scattering pattern of coupled target is distorted under the conditions of distance not satisfy the far field. By analyzing the relationship between near-field and far-field of coupling targets, an extrap- olation method of ＂multiple-transmitter and multiple-receiving＂ is proposed. Firstly, the bistatic data of near-field at each an- gles are measured and extrapolated. Then the extrapolated data can be equivalent to ＂far-field transmitting, near-field receiv- ing＂ data by the reciprocity theorem. Secondly, these data should be extrapolated again due to meet the ＂far-field transmit- ter, far-field receiving＂ conditions. Finally, diagonal elements is selescted to be the monostatic radar cross section （ RCS ） at each angles. By creating a dihedral angle model which has strong coupling mechanisms, through the simulation with FEKO and MATLAB, the far-field RCS is compared with the result of extrapolation by multiple-transmitter and multiple-receiving. The results obtained by this method show a good agreement with the RCS of the far-field, and the average error is less than 1 dB, which verifies the method is effectiveness.