Perturbation theorems for waveguide junctions, with applications

Perturbation theorems. - Our perturbation theorems are stated in the context of a theory of waveguide junctions. A waveguide junction is a linear electromagnetic system possessing ideal waveguide leads and is subject to excitation only through nonattenuated modes in these leads. The domain of the electromagnetic field is the finite region V; the surface S, the complete boundary of V, consists of a part S/sub o/, coinciding with a perfectly conducting surface, and the parts S/sub 1/, S/sub 2/, . . . , S/sub n/ , where S/sub m/ is the terminal surface in the mth of the n waveguide leads.