Transient scattering of dipole field from a conducting cylinder buried in a lossy medium

The properties of transient electromagnetic fields transmitted from an antenna and scattered from buried objects are investigated in connection with the radar imaging of an invisible target (e.g., underground imaging). The early-time scattering fields are calculated exactly when a short horizontal dipole is located over the interface separating air and the lossy medium, and a perfectly conducting infinite cylinder is buried in the lossy medium. The approximate transient scattering fields are also derived and compared with the exact transient field. It is shown that the present approximation is good when the antenna deviates from directly over the buried cylinder, but invalid when the antenna is located over the buried cylinder. It is also found that the geometrical-optics approximation is effective only when the propagation path is nearly normal to the ground surface.<>