Fig. 1. [in Chinese]

Fig. 2. Two-layer imagery: (a) the diagram of EWK algorithm; (b) the computational complexity with increased number of P

Fig. 3. The standoff GPR design: (a) is the schematic of the circuit design; (b) is the experiment setup; (c) is the extension module; (d) are made of aluminum alloy sized 7 cm×7 cm with smooth surface, and (e) is a resolution plate sized of 25 cm×14 cm, and slot starts from 4 mm to 2.5 cm

Fig. 4. Velocity estimation: (a) is the target curve and (b) is the clutter curve.

Fig. 5. Results for resolution plate buried in sand for 8 cm. (a) image by PSM, (b) image by EWK, (c) 3D image, and (d) depth trace result

Fig. 6. Results for targets covering with grass and in sand.(a) O shape (b) X shape (c) 3D image, (d) depth trace

Fig. 7. Without grass and X shape is buried for 15 cm.(a) O shape and (b) X shape