The explore in the depths of earth and prediction and detection of structures and objects within it has been the interest of researchers. In the last few decades, this work has been developed with different approaches such as geology, depthometry, cavity detection, and detection of metallic and non - metallic targets such as mine. One of the non - destructive techniques is the use of electromagnetic waves emitted by the reflection of a wave of buried objects and scatterers in the earth, in order to estimate the position, shape, and size of targets which done by GPR radars. Therefore, the use of GPR radars in different kinds and with military and non-military motivations is pervasive, and extensive researches have been done to improve its performance in different environments. The GPR radars can be divided into two categories: DLGPR and FLGPR. The DLGPR model is more common because of ease to use, lower complexity, better cost and better power return, but in cases such as mine detection and safe distance observance from the polluted area (standoff distance) as well as the very large extent of the area studied, the use of DLGPR is not possible. In this dissertation, the common methods in GPR imaging are investigated and compared. Moreover we extend the LRM method proposed in DLGPR mode to the FLGPR mode that will gain the performance compared to the other methods. Moreover, a method for improving the image resolution by changing the angle of view and forming synthetic aperture radar in cross range of antenna array. On the other hand, whereas the imaging area level is usually not smooth, we investigated the generalization of the proposed method for these conditions by considering the SIRV distribution for the clutter. Finally, using the recently proposed SFET detector, the imaging performance has been improved GPR, FLGPR, Back Projection, Migtation, Imaging,GLRT Detector,Separeting Function Estimation Test