transmission line charastristic impedance

[mohammadsdtmnd]

I'm really confused with it:
https://www.edaboard.com/threads/185425/
please explane it for me exactly what must I do:bang::thinker:

 

[nomigoraya]

So what is point of confusion...
Post is self explanatory
If you have any confusion come with explicit problem statement and then we can discuss
It is easy stuff

 

[mohammadsdtmnd]

exactly where is charasteristic impedance?
Z0 in rectangular plot?

if we have one line that two end of it is terminated bye waveport.
and is there a diffrence between two wave ports Z0?
because theyre not exactly the same .
why theyre not constant and vary bye frequency.
because i though that charastristich impedance is not depend on frequency.

 

[nomigoraya]

First thing your premise that characteristic impedance does not depend on frequency is wrong as for Transmission Line model it is directly function of frequency.
For overview have a look at
https://www.microwaves101.com/encyclopedias/characteristic-impedance
I am sure you are confusing characteristic impedance with the characteristic impedance of free space which is constant and is 50 Ohms
Feel free if this explanation does not make sense for you

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There are two things characteristic impedance and interstice Impedance
Have a look at the article

 

[zorro]

I am sure you are confusing characteristic impedance with the characteristic impedance of free space which is constant and is 50 Ohms

Surely you mean the impedance of free space, that is ≈377 Ω (not 50 Ω).
I don't think this is the confusion of the OP.

There are two things characteristic impedance and interstice Impedance

You mean intrinsic (non interstice) impedance.
Again, this is not related with the OP.

Hi nomigoraya,

As a good and usual approximation, Z0 of a transmission line is considered constant (and purely resistive) in the frequency range for which the line is intended.
But, rigurously speaking, in general it is complex and a function of frequency.