What is Characteristics Impedance?

[powersys]

Hi,

Based on my understanding, characteristic impedance is the constant and instantaneous impedance a signal sees as it travels along a transmission line. If the impedance along the line is different, then the voltage will get reflected. Kindly correct me if I am wrong. But
[1] what is causing the voltage to be reflected?
[2] has characteristic impedance related to the resonant in the LC circuit?
[3] is it necessary that the transmission line be purely resistive or could it be a combination of RLC network that form a 50ohm impedance line?

Kindly advise and thank you for the help.

 

[FvM]

You'll find a good explanation of transmission line behaviour in the open book project Lessons in Electric Circuits, Part II AC, Chapter 14

A more exact description can be found in theoretical electrical engineering text books.

Generally, the real characteristic impedance of a transmission line doesn't involve resistive behaviour, because no losses are implied.
As the formula Z0 = √L/C clarifies, it's formed by reactances, and a lossless tranmission line can be modelled (with limited bandwidth)
by a L/C chain.