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AC impedance of a dipole

Posted Dec 3, 2013, 8:02 a.m. EST Low-Frequency Electromagnetics, Modeling Tools & Definitions, Parameters, Variables, & Functions, Results & Visualization Version 4.3a 3 Replies

Anthony Lethuillier
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Hello,

I am at the moment trying to simulate a simple system and I am having a few problems.

I am trying to calculate the self impedance of a dipole located inside a full space of conductivity 0 and permittivity 80.

The dipole is composed of two electrodes represented by two spheres, one is at a potential of 1V and the other is set at the ground. I put the spheres in a rectangle representing the full space.

I would like to plot the self impedance of the dipole as a function of frequency. The self impedance can be expressed as :

Z = (Vt2 - Vt1)/i

Where Vt2 and Vt1 are the potential of the two electrodes and i is the current fed to an electrode. I do a study with in frequency domain : range(1,10,1000).

I then attempt to plot a 1D plot -> Global with frequency in x axis and impedance in y axis.

I do not know what to put in the expression for the Y axis, indeed i would like to plot the formula above but I am unable to find how to express Vt1, Vt2 and i. Is it possible ?

Is there a way to plot directly the self impedance of the dipole with Comsol ?

Thank you very much for your help

Anthony
3 Replies Last Post Dec 4, 2013, 6:30 a.m. EST
Edgar J. Kaiser Certified Consultant
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Posted: 1 decade ago Dec 3, 2013, 10:26 a.m. EST

Anthony,

one way to measure the current is to use terminal BC and a circuit physics node that connects to the terminals.

Cheers
Edgar

--
Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
Anthony, one way to measure the current is to use terminal BC and a circuit physics node that connects to the terminals. Cheers Edgar -- Edgar J. Kaiser emPhys Physical Technology http://www.emphys.com
Anthony Lethuillier
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Posted: 1 decade ago Dec 4, 2013, 5:05 a.m. EST
Hello following your advice I made a few changes to the model :

- I put a Terminal at the receiving electrodes (Electric Currents -> Terminal 1 -> I0 = 1A)
- I put an electric potential on the transmitting electrode (Electric Currents -> Electric Potential 1 -> V0 = 1V)
- I put the boundaries of the rectangle at the ground potential as the condition at infinity.

I then complete the study and try to plot the impedance (ec.Z11) as a function of frequency. The plot gives me a constant Impedance not varying depending on frequency (which is unexpected) . I feel I am still doing something wrong.
Hello following your advice I made a few changes to the model : - I put a Terminal at the receiving electrodes (Electric Currents -> Terminal 1 -> I0 = 1A) - I put an electric potential on the transmitting electrode (Electric Currents -> Electric Potential 1 -> V0 = 1V) - I put the boundaries of the rectangle at the ground potential as the condition at infinity. I then complete the study and try to plot the impedance (ec.Z11) as a function of frequency. The plot gives me a constant Impedance not varying depending on frequency (which is unexpected) . I feel I am still doing something wrong.
Edgar J. Kaiser Certified Consultant
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Posted: 1 decade ago Dec 4, 2013, 6:30 a.m. EST

Anthony,

the reference impedance is a predefined value. That's not what you need. Look at some examples using circuit physics. Search on the forum and the knowledge base.

Cheers
Edgar

--
Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
Anthony, the reference impedance is a predefined value. That's not what you need. Look at some examples using circuit physics. Search on the forum and the knowledge base. Cheers Edgar -- Edgar J. Kaiser emPhys Physical Technology http://www.emphys.com

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