Dear antenna
I think it is more useful to solve this problem analytically & use CAD's software for complicated problems so you can simulate 2 coax. line that can guide TE & TM mode in addition to TEM modes & then marginal conditions ...
If you want more information do not hestitate
Hi raymond
I think you should use internet search as a good choice more, the previous link was one of the firs suggestions in google search & I offer you more
(but you can find it yourself)
for Demo:
http://rf.rfglobalnet.com/software_modeling/software/15/422.htm...