Abstract: The detection of shallow two-dimensional objects in layered media by using time domain scattering data is considered in this paper. A volumn integral equation which relates the scattering fields in time domain with the permittivity of the objects is obtained by volumn equivalence principle. The equation is transfered into frequency domain and the inversion equation is obtained after discretion. With our iterative method both forward and inverse problems are solved in each iteration. The forward problem is solved by using finite-difference time-domian method. The inverse problem is carried out by using a pseudoinverse technique. The Green function excited by line current source is derived by using plane wave expansion method. Several examples are given to show the ability of this metohd to invert arbitrarily shaped objects.

Key words: layered media, shallow two-dimensional objects, finite-difference time-doman, plane wave expansion method, pseudoinverse texhnique