抑制穿过具有倾斜角度的介质探测成像时产生的寄生干涉条纹现象

Restraining parasitic interference fringe phenomenon in detection imaging through the medium with inclined angle

进行穿透扫描探测实验时,在回波图像中发现了由于介质具有倾斜角度产生的周期性干涉条纹,这种干涉条纹对介质后或者介质中的目标成像有严重影响.研究表明,这种干涉条纹主要由介质表面反射波及透射后的层面反射波引起.文中建立点源辐射模型分析干涉条纹现象的形成机理,推导出薄层介质的干涉条纹间距表达式.考虑到天线的影响,建立了角锥喇叭天线近场模型,并且基于该模型进行精确的电磁仿真.商用软件Computer SimulationTechnology的电磁仿真结果与MATLAB程序的数字计算结果进一步验证了干涉条纹的成因分析及其与介质倾斜角度的关系.从推导的薄层介质干涉条纹间距表达式可以看出,干涉条纹间距与介质倾斜角度有关,控制影响条纹间距的因素,可以抑制干涉条纹现象,从而达到提高目标分辨率和成像质量的效果.

Some periodic interference fringes due to medium with inclined angle are found in the echo image when the medium plate is inclined in the penetrating experiment. These interference fringes have serious influence on the imaging result of the interesting target. The study indicates that the interference fringes are caused by the reflected waves, which mainly come from the surface and below layer of the medium plate. To analyze the interference fringe phenomenon, a point source model is constructed in the paper, and the expression of the spacing between the adjacent interference fringes is derived. When the factor about antenna is taken into account, the pyramid horn near-field model is constructed. Based on it, the accurate electromagnetic simulations are performed. The results of the commercial software CST and MATLAB calculation both confirm the analysis about the interference fringes and the relation with the inclined angle of the medium plate. From the expression of the thin medium, the spacing between the adjacent interference fringes is related to incline degree of the medium. Controlling the influence factors of the spacing between fringes can restrain the interference fringe phenomenon in order to improve the target resolving power and imaging quality.