THE EXPANSION WAVE CONCEPT - PART I - EFFICIENT CALCULATION OF SPATIAL GREENS-FUNCTIONS IN A STRATIFIED DIELECTRIC MEDIUM

A procedure is given to perform the inverse Fourier transformation rel ating a spatial Green's function to its spectral equivalent. The proce dure is applied to the spectral Green's functions of the double scalar mixed-potential integral expression formulation of the electromagneti c field in a stratified dielectric medium, The extraction technique is used to annihilate every type of ''problematic'' behavior of the spec tral Green's functions. Every annihilating function is inverse Fourier transformed analytically. It is shown that the annihilation of both t he surface wave poles and the singularities at the branch point result s in a set of analytical spatial functions, which are a very good appr oximation of the exact spatial Green's function down to relatively sma ll lateral distances. Some very important characteristics of these fun ctions will play a crucial role in Part II of the paper, where a new t echnique is introduced to model mutual coupling.