While it isn't a book, and won't help you there, you might check out my Syrup package for analyzing electric circuits. It is available at the Maple website in the Applications section. It can read spice decks and symbolically solve them. For example,

with(Syrup):
ckt := "
V1 1 0
R1 1 2
C1 2 0
.end":
syrup(ckt, ac);

                       /                      V1     \ 
                      { v[1] = V1, v[2] = ----------- }
                       \                  1 + s C1 R1/ 
dsolve(syrup(ckt,tran));
                                          /    t  \   
                       v[C1](t) = V1 - exp|- -----| V1
                                          \  C1 R1/   

Alas, it doesn't have a transmission line element, but you might find it useful, regardless.

The pdf mentioned above uses Maple V R3, or perhaps earlier, and so is a bit dated. There's nothing on transmission lines shown in the index. Out of curiosity I checked a simple example about radioactive decay: the answer shown was wrong!

J. Tarr