I am running an electromagnetic 2D solver (Q2D extractor) for finding RLGC parameters. I have a microstrip as shown below enter image description here

I am varying loss tangent of the surrounding medium, keeping the relative permitivity of the medium constant. I am getting a capacitance per unit length value that is same for any non-zero value of loss tangent, but different when loss tangent is 0. How is this possible? The graph below should explain my doubt clearly. Note: I have taken hypothetical values for loss tangent values.enter image description here


1 Answer 1


Does capacitance per unit length change with change in loss tangent of surrounding medium?

If the permittivity of the medium remains constant then no, capacitance per unit length change does not change with loss tangent variations.

It's the same for inductance per unit length - having greater copper losses does not affect the inductance of a wire.

  • \$\begingroup\$ Thanks for the clarification. Can you explain why I am getting results as shown in the graph, in my question? The results are from a commercial solver \$\endgroup\$
    – skt9
    Mar 26, 2017 at 5:04
  • \$\begingroup\$ Talk to the people providing the solver. It shouldn't happen so either you or they have got something wrong. \$\endgroup\$
    – Andy aka
    Mar 26, 2017 at 9:40

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