A conjugate gradient procedure for the analysis of planar conductors with alternating patch and aperture formulations (EM scattering)

The formulation of an electromagnetic scattering problem by an operator equation can be done in different ways leading to different rates of convergence when the conjugate gradient algorithm is used. The convergence can tend to slow down at certain stages, depending on the formulation used. Thus, whenever the error tends to level off in one formulation, it is advisable to switch to another one. To this end a procedure that alternates repeatedly between formulations is presented. It is shown to accelerate the convergence rate during the earlier stages of the iterative process, making it possible to arrive at a prescribed practical error criterion faster. A substantial saving in storage allocation is attained.>