ITERATIVE ANGULAR-MODE INVERSION OF A CONDUCTING CYLINDER

For the iterative reconstruction of the shape function of a two-dimens ional conducting object, the angular modal representation of the scatt ered field gives effective choice of measurement points especially in the presence of noise in the scattered field. It is shown that the obj ect center and its initial shape may be estimated from the effective p ropagating modes of the measured scattered field. By employing N effec tive propagating modes excluding the exponentially small higher-order modes, numerical calculation shows that the reconstruction of the shap e function with 2N unknowns is possible. When the noise is present, th e characteristics of the cost function show that the effective propaga ting modes with multiple incident waves eliminating the shadow region of the object are needed for the stable inversion. (C) 1995 John Wiley & Sons, Inc.