ABSTRACT
The relevant modification of the quasi-isotropic approximation (QIA) was implemented by Naida. The QIA matches quite naturally the classical Budden and Courant-Lax methods. The virtues of the QIA are that it applies not only to a plane-layered medium, as the Budden method does, but also to 3D inhomogeneous media. The transition from the “split” version of the QIA to the non-interacting normal waves is accomplished by going through the same intermediate stages as when considering the non-split form. The matching procedure becomes considerably simpler if one uses equations for the electric induction vector in the form for split rays. In an anisotropic medium, the list of instruments can be supplemented by polarizers performing the selection of polarization, and by travelling wave antennae discriminating between ordinary and extraordinary waves by their phase velocity.
