Fast evaluation of zero-offset Green's function for layered media with application to ground-penetrating radar

We propose an efficient integration path for the fast evaluation of the three- dimensional spatial- domain Green's function for electromagnetic wave propagation in layered media for the particular case of zero- offset, source- receiver proximal ground- penetrating radar ( GPR) applications. The integration path is deformed in the complex plane of the integration variable k(P) so that the oscillations of the dominant exponential term in the spectral Green's function are minimized. The contour does not need to be closed back on the real k(P) axis as the complex integrand rapidly damps. The accuracy and efficiency of the technique have been confirmed by comparison with traditional elliptic integration contours. The proposed algorithm appears to be promising development for fast, full- wave modeling and inversion of GPR data.