Autofocusing Imaging and Medium Parameter Estimation Based on Phase Error for Penetrating Radar

Penetrating radar has the ability to detect the targets buried inside or hidden behind mediums. Most imaging algorithms are only effective when the medium parameters are known. However, it is difficult to obtain the exact information of the medium in real scenarios. Therefore, the error of unknown parameters leads to defocusing of the obtained image. To solve this problem, an autofocusing imaging and parameter estimation method based on phase error is proposed in this paper. First, the relationship between phase error and medium parameters is derived. Then, by analyzing the linear relationship with respect to the frequency, the phase error and optimal depth are determined. The autofocusing process is realized by compensating the defocused image with the estimated phase error. Finally, the relative permittivity of the medium and depth can be obtained by solving the established function. The effectiveness of the proposed method is validated by experiments.