An Adjoint-Field Technique for Shape Reconstruction of 3-D Penetrable Object Immersed in Lossy MediumImmersed in Lossy Medium Articles uri icon

publication date

  • February 2009

start page

  • 520

end page

  • 534


  • 2


  • 57

International Standard Serial Number (ISSN)

  • 0018-926X

Electronic International Standard Serial Number (EISSN)

  • 1558-2221


  • An inversion algorithm is presented that is based on hybridization of the adjoint scheme for calculating gradient directions with the method of moments. The goal is to reconstruct the shapes of 3-D objects immersed in a lossy medium. The irregularshape of the reference object is modeled by a representation with spherical harmonics functions, whereas during the reconstruction, individual surface nodes are updated. In the adjoint scheme, gradient directions for the least squares data misfit cost functional are calculated by solving the forward problem twice in each iteration,regardless of the number of spherical harmonics parameters used in the reference model or the number of surface nodes used for the discretization of the shapes. The numerical results show that implementing the well known frequency hopping technique helps the algorithm avoid dropping in local minima.