TM problem:?interesting geometries

[kwantumplanck]

hi,

i wrote a program which is able to calculate the Transverse Magnetic problem for a Perfect Electrical Conductor structure and a given infalling (correct english term?) wave. It works for a circular cilinder and braggreflector, and i am looking for a problem that is a bit more adventurous. Does someone know which geometry could give some nice results? i hoped for a pattern with fractal structure but suppose something like that doesn't exist. thanks in advance!
david