Microwave holographic imaging of underground objects

The resolving capability of underground imaging radar employing a multifrequency holographic approach is characterized in terms of controlling parameters such as the synthetic aperture length, soil conductivity and dielectric constant, and antenna beamwidth. The propagation velocity of electromagnetic wave in soil, which varies from soil to soil, is an essential parameter for reconstructing object images using the holographic approach. Hence, a method of estimating the propagation velocity and also the depth of an object from a pulse-echo image based on the minimum squared error is proposed. The result of underground object image reconstruction from real pulse-echo data is reported to demonstrate high estimation accuracy of the propagation velocity and fine resolution of the reconstructed image.