1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Series Resistance with Ansoft Maxwell SV for coax

  1. May 5, 2009 #1
    Hello, can anyone assist me in building a geometric model of an RG58 coax cable with Ansoft Maxwell SV using the appropriate solver to solve for the series impedance of the cable per unit lenght. The Ansoft Help files available do not cover this.
  2. jcsd
  3. May 5, 2009 #2


    User Avatar
    Science Advisor

    I don't know that modeling program, but if you would like to calculate the characteristic impedance of coax, the following might be useful:

    This is for air-cored coax cable :
    Z = 138 log ( D / d )

    where Z is the characteristic impedance
    log is the log to the base 10
    D is the inside diameter of the outer conductor
    d is the outside diameter of the inner conductor.

    D and d must be in the same units as each other.
    .................eg if D / d = 5 then Z = 96 ohms

    The characteristic impedance does not depend on length but is a property of the cable.
  4. May 7, 2009 #3
    Thanks for the help, but my problem is really using ANSOFT MAXWELL SV to build a model to solve the series resistance of the coax and the ac resistance of the coax. The software version I am using is the student version(SV) and ansoft has not published much tutorials on using their software. I think the problem is confined to selecting the correct geometry and using the right solver, but of which I am not sure.
  5. May 7, 2009 #4
    Modelling a coax cable with ansoft maxwell sv

    1. The problem statement, all variables and given/known data
    Use Ansoft Maxwell SV to determine the series resistance, conductance, capacitance, inductance and Ac resistance of a coaxial cable by building a simple geometric model and simulating it with different solvers. The cable is RG58.

    2. Relevant equations
    All the relevant values used for the software were obtained from the RG58 spec sheet.

    3. The attempt at a solution
    I have found the conductance, inductance and capacitance using the electrostatic and magnetostatic solvers. My geometry consists of 3 concentric circles, a core ( tinned copper - 0.37" diameter), a dielelectric(foam polyethylene of 0.114" diameter) and the shield or braid( tinned copper diameter - 3.32mm).
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook