真实地形环境下低空雷达目标回波信号分析

Analysis of Echo Signals from Low Altitude Radar Targets in Actual Landform

针对低空雷达目标与杂波、环境难于一体化建模的问题,提出了一种分析真实地形环境中低空飞行目标的雷达回波信号的实景相干复合方法(CHIAL).以机载脉冲多普勒(PD)雷达为平台,首先将半空间并矢格林函数引入物理光学方法中,结合图形电磁学计算低空目标的雷达散射场强度,然后利用地形高程数据和地形地物分析数据,得到杂波单元的散射特性,通过相干杂波模型产生地杂波,最后将所有雷达回波送入各自的距离门,并加入噪声信号,模拟包含目标特性和杂波特性的有效回波信号.与传统复合建模方法相比,CHIAL方法的目标回波信号和杂波信号更加准确.对机载PD雷达探测低空目标的仿真实验表明,CHIAL方法在处理90m×90m地形高程数据时,杂波分布和信杂比与理论分析基本一致,有很强的系统工程实用价值.

Focusing on the difficulty in integrative modeling among the low altitude radar targets, the ground clutter and the environment, a coherent hybrid method in actual landform （CHIAL） is proposed to analyze the echo signals from radar targets in actual landform environment. Based on airborne pulsed Doppler （PD） radar, a half-space physical optics integral equation is deduced by introducing the half-space Green＇s function into the physical optics method. The radar cross section of conductive targets is calculated in the half space by combining the graphicalelectromagnetic computing method. The scattering of the clutter cell is computed with SRTM and DFAD data, and the ground clutter is produced by using the coherent clutter model. After mixing with noise, the signals are then sent into corresponding range gates. Simulations on the efficient echo signals with the target peculiarity and clutter peculiarity show that the proposed method is more accurate than traditional hybrid modeling methods. Numerical results on airborne PD radar detecting tow altitude targets show that the clutter distribution and the signal-to-clutter ratio accord with the theoretical analysis in using 90 m×90 m landform height data, and that the method is applicable in system engineering