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How We Will Proceed

In the early chapters we will focus on the behaviour of transmission lines which will be

frequently of the twin linę or coaxial linę structure. The lines are usually uniform in

cross section with respect to the longitudinal direction. Magnetic fields will usually be

completely transverse, and a distributed Circuit treatment will be possible.

An important property of the transmission lines is that once you take into account

the effects of distributed Circuit theory, the current and voltage at one end of the linę is

seen to be not the same as the current and voltage at the other. Clearly in this context

the wires of transmission linę are not behaving as the conductors of a lumped Circuit in

which the potential has the same value all the way along the wire (except for the effect of

resistance) and the current entering one end of the wire is the same as the current leaving.

Later in chapters 8 to 11 we will have to consider morę complex geometries for signal

transmission, in which situations magnetic fields in a longitudial direction make it

necessary for us to use a morę generał treatment based upon electromagnetic field theory.