Well, in most applications it is the tank circuit that matches a stage (amplifier in the case of transmission lines)
to the line itself.
A tube amp (IE:) has a very high impedance output. Coupling to a low impedance line. the tank circuit is designed to closely 'match' these two impedance's.
Complex impedance makes little sense to me, look at impedance as being purely resistive.
Learning this confused me a lot until I understood it, soon you will understand also.
Hope this helps
Complexity with transmission lines comes from standing waves on the line.
The line has two end that have to closely match their fed device. (another amp, transformer, antennae, microphone, etc.) the closer this match, the less standing waves and the greatest transfer of power coupling.
Not as simple as inserting a series resistance as in most cases you are dealing with AC, a different animal.
Often frequency ranges from audio through many Ghz microwave.