单脉冲寻向天线和目标的一体化仿真及测角误差分析

本文通过矩量法及其高效数值方法（MLFMA）对近距离目标--单脉冲收发天线的电磁互作用进行一体化数值仿真，定量研究了单脉冲天线的近场角度测量特性.在该近场模型中，目标散射近场的幅、相分布和同轴探针激励的喇叭单脉冲天线的辐射场（对应远场和波束）、接收端响应（对应远场差波束）均采用全波数值模拟获得.首先，计算单脉冲天线的辐射场并将其作为对目标照射的激励条件；接着，计算目标散射近场的空间分布；并计算出单脉冲天线所接收到的目标散射场；最后，使用幅值法和相位法计算出单脉冲天线近场测角角度，并在此基础上对近距离测角误差进行研究.在导弹目标算例中，将天线--目标一体化建模和天线口径面上散射近场的幅、相分布计算结果用于近距离条件下单脉冲天线测角误差的研究，并通过频率、距离的变化对测角精度做了对比分析；发现目标近场散射幅、相分布的非均匀性，是导致单脉冲天线近距离角度测量产生较显著的测角误差的主要原因；而频率较低时，测角误差较小.文中给出了物理解释，并提出近距离测向时借助于较低频信号的校正以降低测角误差的建议.

Integrated Simulation and Angle Error Analysis of a Mono-Pulse Antenna

The globalized simulation of the response of the mono-pulse antenna in the near field region of the scatterer is done by using the method of moment(MoM)and the multi-level fast multipole algorithm(MLFMA) to evaluate quantitatively the performance of the angle measurement in near range for mono-pulse antenna.In this model the amplitude and the phase distribution of the scattering field in near region,and the radiation and the receiving response of the mono-pulse antenna are calculated accurately through the full wave analysis.First,the radiated field from the antennas with the summation beam,as the incidence to illuminate the target,is calculated.Then,the scattered field in the near region produced by the target,as the incidence to the received antenna,is simulated numerically.Finally,the electric signals received by the antennas with the difference beams are calculated and the measured angle is obtained by using the phase-comparison or the amplitude-comparison of the signals received from difference beams.The errors of the measured angles and its sources are discussed.The numerical results in the example with a missile-like target show that the angle measurement based on the summation and the difference beams of the mono-pulse antenna in the near field result in remarkable errors,and the application of the signals with the relative lower frequency dead to the less errors of the angle measurement.The corresponding physics behind above phenomena is given and the recommendation of the lower frequency signal for near range measurement is presented.