基于频率分集探地雷达的介质参数估计方法

Medium parameter estimation method based on frequency diversity ground penetrating radar

针对地下目标体周围介质参数估计问题,提出一种基于图像熵的介质参数估计方法。首先推导了介质条件下频率分集阵列探地雷达的点扩展函数,分析了点扩展函数与后向投影成像算法之间的联系,然后将频率分集探地雷达与超宽带探地雷达成像结果做了对比分析。对于同一块包含目标的待成像区域而言,介质参数对电磁波的传播速度有较大的影响,当采用不同的介质参数分别对该区域进行成像时,得到的成像结果亦不相同。对不同参数下的成像结果进行图像熵的计算,成像结果的图像熵值越小,则在使用该参数时成像的聚焦度越好,所对应的介质参数越接近其真实值。实验结果表明:在介质的电导率不为零时,频率分集探地雷达较超宽带探地雷达在目标定位成像方面具有更好的效果,且当目标为细长目标体时,所提出的参数估计方法能够对目标体周围介质参数进行有效估计。

Aiming at the problem of medium parameter estimation around buried objects,a method of medium parameter estimation based on image entropy is proposed.Firstly,the point spread function(PSF)of frequency diversity array ground penetrating radar(FDA-GPR)in medium is derived,and the relationship between PSF and back projection imaging algorithm is analyzed.Then,the imaging results of FDA-GPR and UWB-GPR are compared and analyzed.For the same region containing the target to be imaged,the medium parameters have a great influence on the propagation velocity of electromagnetic wave.When different medium parameters are used to image the region,the imaging results are also different.The image entropy of the imaging results under different parameters is calculated.The smaller the image entropy of the imaging results,the better the focusing degree of the imaging,and the closer the corresponding medium parameters are to their true values.The experimental results show that:when the conductivity of the medium is not zero,FDA-GPR has better performance in target location and imaging than UWB-GPR,and when the target is a slender target,the proposed parameter estimation method can effectively estimate the parameters of the medium around the target.