An improved split-step technique for numerical modelling of propagation in the troposphere

A framework has been presented in which paraxial solutions of the vector wave equation in a stratified medium can be computed, based on the exact Maxwell equations. Two techniques to refine the commutation error were outlined. Central to the method, however, is the use of a similarity operator transformation to approximate the first order matrix equations. Since there is no arbitrary truncation of the initial equation, the method also allows coordinate transformations to be introduced in a natural way. It was shown that a combination of a coordinate transformation and a (gauge) transformation of Maxwell´s equations permits separation of the coupling effects of the refractive and admittance inhomogeneities