We were being taught about Lattice networks in class, today, and our professor mentioned that the characteristic impedance of a symmetrical lattice network like
is given by:
I'm not sure what characteristic impedance means in this context. I searched around the net a bit and found that the term is generally used in the context of transmission lines. However, I'm not sure how it applies to a lattice network or perhaps more generally to a two-port network.
Basically, my question is: What is the definition of characteristic impedance of a lattice network (or a two-port network)?