TABLE OF CONTENTS In order to obtain a unique solution of the Maxwell field equations, one should impose the appropriate boundary, radiation and edge conditions. In this context two facts should be particularly emphasised:
the radiation condition applies to the total field, but not to each mode individually, since the latter need only be finite at infinity;
the edge condition is a special kind of boundary condition that, in the presence of surface singularities, must be applied in order to ensure a unique solution of the field problem (see e.g. [10, p.89]) .
Let us consider a regular surface S of a medium discontinuity, as shown in Figure 2.1, where the subscripts 1 and 2 distinguish quantities in regions 1 and 2 respectively. By considering (2.13) and (2.14) as a consequence of a limit process it is easy to obtain the following conditions:
| (2.45) |  |
| (2.46) |  |
where J and M are respectively the electric and magnetic surface current density distributions at the interface.
Similarly, by considering (2.15) and (2.16) and a small volume at the interface, after a limit process one obtains,
| (2.47) |  |
| (2.48) |  |
where ? and ? m are respectively the electric and magnetic surface charge density distributions on the interface.
If neither medium is perfectly conducting the tangential component of the fields E and H are continuous while their normal components undergo a jump corresponding to the discontinuity in the...
