频率步进探地雷达的SAR成像处理方法

SAR Imaging Processing Method of the Stepped-Frequency GPR

由于冲激脉冲探地雷达平均功率低,限制了其作用距离和探测深度,多用于近地表和浅低层探测。为了提高系统的作用距离和探测深度,常采用频率步进探地雷达。利用频率步进信号的大带宽和高平均功率的特点,不但可以提高作用距离和探测深度,而且成像分辨率可以大为改善。由于介质与空气的介电特性不一致,电磁波的传播路径和传播速度会发生相应的改变,常用的回波模型和合成孔径成像方法不再使用。本文推导出了频率步进探地雷达的回波信号模型,并结合SAR成像理论,针对地下目标探测的特点,提出了分层聚焦的SAR成像处理方法,取得了良好的效果。

The low average power of the impulse ground penetrating radar （GPR） limits its coverage range and depth, so it could be applied in detection of near ground ＂surface and sub-surface. Normally a stepped-frequency GPR is used to increase the coverage range and detection. The Stepped-frequency GPR could not only increase the coverage range and detection depth with its broad bandwidth and high average power, but also improve the imaging resolution greatly. As the dielectric property of the media and of air is different, the electromagnetic wave would change its propagation path and velocity correspondingly. The normal echo model and SAR imaging method will not be used any more. The echo signal model of the stepped-frequency GPR is deduced, combining the SAR imaging theory, and on basis of detection features of the sub-surface target, a layered focusing SAR imaging processing method is presented and the perfect effect is achieved.