squ...@my-deja.com writes:But in fact the terminal impedance of a lossless semi-infinite
> The question is whether the transmittion line can have a non-imaginary
> impedance. Because I doubt the last property is consistent with energy
> conservation. If the impedance is imaginary, this is principally
> different from the resistor.
transmission line is purely real. There is no reactive component.
In an electrical circuit it behaves just like a resistor in that it
absorbs energy. That is not inconsistent with energy conservation,
however, because the energy that the transmission line absorbs is
stored in the electromagnetic fields within the transmission line.
If a voltage or current of finite duration is applied at the terminals
of the line the fields will take the form of travelling waves which
propagate away from the terminals. Because the line is semi-infinite
the travelling wave does not reflect back toward the terminals. That
is not true, by the way, for a line of finite length. The latter does
have a purely imaginary terminal impedance.
This is not so different from an ordinary resistor which dissipates
As I said in a previous post, I highly recommend analyzing the damped
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