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Calculationg current in a cylindrical wire
Posted Sep 24, 2009, 11:18 a.m. EDT 2 Replies
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Hi,
I am working with RF module and I have model in which there is conductor i mean the wire with dimensions H=39.4cm and R=0.6mm. My input is plane wave is z-direction. I have a applied the plane wave and I got the current density plot also. Now my problem is I want to calculate the current along the length of the wire in my model it is along x. Can somebody tell me how to do that? I know we will have alot of cylinders with different current densities but I want to calculate the current for each particular area and sum them.I dont know whether my approach is correct or not so please tell me how to calculate the current along the length of the wire.
I have attached my model file.
Thank You
I am working with RF module and I have model in which there is conductor i mean the wire with dimensions H=39.4cm and R=0.6mm. My input is plane wave is z-direction. I have a applied the plane wave and I got the current density plot also. Now my problem is I want to calculate the current along the length of the wire in my model it is along x. Can somebody tell me how to do that? I know we will have alot of cylinders with different current densities but I want to calculate the current for each particular area and sum them.I dont know whether my approach is correct or not so please tell me how to calculate the current along the length of the wire.
I have attached my model file.
Thank You
2 Replies Last Post Nov 2, 2009, 10:05 a.m. EST
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Posted:
2 decades ago
I don't have your input file, but your description is of a simple straight thin-cylinder (wire) exposed to an input plane wave.
Scenario 1: If I assume that your wire is a perfect conductor, then it will have only surface currents, and no bulk internal (volume) currents. In that case, you can obtain the cross-sectional current at each position along the wire via a line integration of the x-directed surface current around rings on the wire. First, break it up into segments (just so that you will have multiple rings to work with, around the wire). You'll need to integrate the surface current along these circles, one circle for each x value. Set up an edge integration coupling variable (options --> integration coupling variables --> edge variables) and define edge expressions (you could call each one I_n, for various n) with the expression = Jsx_rfw, since your wire current is along x.
Scenario 2: Alternatively, if your wire is not a perfect conductor, then you may have volume currents. There apparently isn't a volume current density variable available in the 3D RF module, but you can integrate (a line integral) the azimuthal component of the H field around the wire, and use Ampere's law to extract the total current inside along the wire. Since your wire is along the x axis, then you must use Hy and Hz to build H_azimuthal. From a little vector analysis, we can see that:
H_azimuthal = (Hz*y-Hy*z)/sqrt(y^2+z^2). (I'm assuming the wire center is at y=z=0. If not, you will either need to move it or introduce offets to those expressions.) The integral of H_azimuthal around each ring (i.e., around the wire) should yield the current inside, by Ampere's law. And again, you can use an edge-type integration coupling variable here to set it up.
Does that help?
Scenario 1: If I assume that your wire is a perfect conductor, then it will have only surface currents, and no bulk internal (volume) currents. In that case, you can obtain the cross-sectional current at each position along the wire via a line integration of the x-directed surface current around rings on the wire. First, break it up into segments (just so that you will have multiple rings to work with, around the wire). You'll need to integrate the surface current along these circles, one circle for each x value. Set up an edge integration coupling variable (options --> integration coupling variables --> edge variables) and define edge expressions (you could call each one I_n, for various n) with the expression = Jsx_rfw, since your wire current is along x.
Scenario 2: Alternatively, if your wire is not a perfect conductor, then you may have volume currents. There apparently isn't a volume current density variable available in the 3D RF module, but you can integrate (a line integral) the azimuthal component of the H field around the wire, and use Ampere's law to extract the total current inside along the wire. Since your wire is along the x axis, then you must use Hy and Hz to build H_azimuthal. From a little vector analysis, we can see that:
H_azimuthal = (Hz*y-Hy*z)/sqrt(y^2+z^2). (I'm assuming the wire center is at y=z=0. If not, you will either need to move it or introduce offets to those expressions.) The integral of H_azimuthal around each ring (i.e., around the wire) should yield the current inside, by Ampere's law. And again, you can use an edge-type integration coupling variable here to set it up.
Does that help?
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Posted:
2 decades ago
Yes it will help me I think I will implement that and will reply you