Super-resolution imaging for point reflectors near transmitting and receiving array

This paper presents subsurface imaging techniques using the well-known MUSIC algorithm to localize point reflectors in cross-borehole radar arrangements. Radar signals received by a spatial array have to be decorrelated, in general, as a preprocessing step when the MUSIC algorithm is implemented. Since most of the decorrelation techniques are based on planar wave incidence model, it is difficult to apply the decorrelation technique for signals from radar targets in the near field of the array. In this paper, we introduce a decorrelation technique with transmitting and receiving array for targets near the array and apply the MUSIC algorithm for estimating the two dimensional position of the point targets in crosshole tomographic measurement. Further, an expanded version of the algorithm to eliminate the direct wave is also derived. Simulation results show that this method offers much higher resolution and accuracy than the conventional diffraction stack method. The paper also discusses the relationship between the SNR ratio and the minimum target separation to be resolved.