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Homework Help: Lossless transmission line characteristic phase constant

  1. Sep 11, 2016 #1
    1. The problem statement, all variables and given/known data

    A lossless transmission line has an inductance of 9.0 nH / m and a capacitance of 3.6 pF / m.
    a) What is the line's characteristic impedance?
    b) Calculate the phase constant of a frequency of 1 GHz.

    2. Relevant equations

    Equation of characteristic impedance of a transmission line:

    Z0 = sqrt( R+j2piL / G+2jpiC )

    Where R and G = 0, because lossless transmission line.

    3. The attempt at a solution

    For a I just used the equation above, but for task 2 I'm not sure what to do. I dont now how to get Sin/Cos to the equation so I can fint the phase constant. Do I need to do something to the equation above?
  2. jcsd
  3. Sep 13, 2016 #2

    rude man

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    For a lossless or for that matter distortionless line there is a very simple formula relating the phase constant to the radian frequency, inductance per unit length and capacitance per unit length, all of which you have. SI units are rad/m.
  4. Sep 13, 2016 #3
    Thanks a lot for you respons. I really appreciate it. Do you know what the formula is, or where I could find it? I have seen in the book, but cant find it. Also I have added what I done in the first task. Should I use the result from that? I got 50 ohm.

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  5. Sep 13, 2016 #4

    rude man

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    There are many places on the Internet where you can find that formula. No, that formula does not include the answer to part (a).
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