Multilevel evaluation of electromagnetic fields for the rapid solution of scattering problems

A multilevel algorithm is presented for evaluating fields generated by given distributions of electric current. The algorithm can be used to accelerate the solution of scattering problems using the method of moments and/or boundary element methods. The algorithm exploits the limited number of degrees of freedom that characterize a field observed over a domain that is well separated from a source domain. Both the memory requirements and the computational complexity of the algorithm are O(Ns log(Ns)), where Ns is the common number of sources and observation points. The multilevel algorithm can easily be incorporated into existing method-of-moments (MoM) programs. A simple physical interpretation of the algorithm is provided. © 1994 John Wiley & Sons, Inc.