Near-field modal decomposition using Huygens´ principle and equivalent sources

A modal expansion of the electric field induced within a lossy medium by an arbitrary antenna is proposed. The technique is based on equivalence theorem or Huygens principle. Equivalent sources on a surface are defined to represent an arbitrary antenna. Using Singular Value Decomposition, we are able to determine the orthonormal modes that can be used to decompose the E-field. The basis can then be applied for the measurement of the field distribution within a lossy medium for e.g. Specific Absorption Rate (SAR) measurement.