“…Several authors (Balanis, 1989;Collin, 1973Collin, , 1991Felsen & Marcuvitz, 1973;Freeman, 1950;Harrington, 1961;Kurokawa, 1958;Tai, 1971;Van Bladel, 1952) have obtained results on this issue for separate cases of (i) variable ε, µ but no sources and (ii) certain types of sources but uniform ε, µ. We shall present here a series of theorems that generalize these results and ultimately show that the TE/TM modes are complete for arbitrary (and not merely piecewise constant) z-variation of ε, µ and arbitrary sources.…”