A Conjugate Gradient Procedure for the Analysis of Planar Conductors with Alternating Patch and Aperture Formulations

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 may tend to slow down at certain stages, depending on which formulation used. Thus whenever the error tends to level off in one formulation, it would be advisable to switch to another one. To this end a procedure which 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. In addition, it is shown that a substantial saving in storage allocation is also attained.