Approximate Boundary Conditions in Electromagnetics

The constants a 1, a 2 , a 3, A 0 and A 1 in Section 5.6.2 are related by (5.213) with ? =
- ? m,
= ? m( m = 1, 2), and, since there are only four equations, it is clear that one constant is undetermined.
When ? =
- ? 1, (5.200) becomes
| (E.1) | ![]() |
and for ? =
- ? 1 we have
| (E.2) | ![]() |
The addition of these gives
| (E.3) | |
where
| (E.4) | ![]() |
and there is an equation similar to (E.3) with ? 1 replaced by ? 2. These are sufficient to specify ? 1 and ? 3 in terms of C. By expanding (sin ? m) -1 sin 3 ? m etc. in powers of cos 2 ? m and using the fact that
| (E.5) | |
it can be shown that
| (E.6) | |
| (E.7) | |
| (E.8) | |
for any ?.
To complete the specification we need another equation connecting C and ?. Subtraction of (E.2) from (E.1) gives

and there is again a similar equation with ? 1, ? 1 and ? 2 replaced by ? 2 , ? 2 and ? 1, respectively. On eliminating a 2 from the two equations, we obtain
| (E.9) | ![]() |
where we have used the fact that
cos 3 ? m = - cos 2 ? m
and by a...