Menu

Discussion Forum

New Discussion
Filtern

Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.

Complex permittivity, permeability and conductivity

Posted 07.02.2018, 18:15 GMT-5 2 Replies

Peter H
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

I am modeling materials-photons interactions. I have created a new custom material which I wish to completely define using complex valued permittivity and permeability numbers and I wish to confirm two things:

1) is the way I have entered these complex values below correct, given that ur, ui, er and ei are defined in my Global Parameters?

Link to image: https://imgur.com/a/NKqAi

2) Even though the physics module I'm using is sampling the "electrical conductivity", does the complex value of permittivity ALWAYS overwrite the suggested imaginary value of permmitvity implied by the conductivity? Stated otherwise, when imaginary permittivity is defined is the conductivity field irrelevant?

Many thanks for the help!

2 Replies Last Post 08.02.2018, 12:05 GMT-5
Sergei Yushanov Certified Consultant
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 7 years ago 08.02.2018, 08:45 GMT-5

Peter,

1) Yes, permittivity and permeability are defined correctly.

2) No, complex value of permittivity doesn't overwrite losses related to conductivity. When you define complex part of permittivity and non-zero conductivity at the same time, it means that total loss is a superposition of polarization loss and conductive loss. This is because permittivity and conductivity enter Maxwell equation not independently but in combination (eps-jsigma/omega)=[(eps'-jeps")-j*sigma/omega].

Good explanation of alternative ways of medium characterization is given in the Table on p. 22 of the following textbook: http://www.sembahome.org/geg/files/2016/02/electrodinamicaprimeraparte.pdf

Regards,

Sergei

Peter, 1) Yes, permittivity and permeability are defined correctly. 2) No, complex value of permittivity doesn't overwrite losses related to conductivity. When you define complex part of permittivity and non-zero conductivity at the same time, it means that total loss is a superposition of polarization loss and conductive loss. This is because permittivity and conductivity enter Maxwell equation not independently but in combination (eps-j*sigma/omega)=[(eps'-j*eps")-j*sigma/omega]. Good explanation of alternative ways of medium characterization is given in the Table on p. 22 of the following textbook: http://www.sembahome.org/geg/files/2016/02/electrodinamicaprimeraparte.pdf Regards, Sergei
Peter H
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 7 years ago 08.02.2018, 12:05 GMT-5
Updated: 7 years ago 08.02.2018, 12:14 GMT-5

Hello, Sergei, I was hoping you would spot my question based on your previous replies to similar questions.

I see the parameterization you are talking about in the textbook and that clears up my misunderstanding -- other sources I was working from weren't as clear.

Thank you,

Peter

Hello, Sergei, I was hoping you would spot my question based on your previous replies to similar questions. I see the parameterization you are talking about in the textbook and that clears up my misunderstanding -- other sources I was working from weren't as clear. Thank you, Peter

Note that while COMSOL employees may participate in the discussion forum, COMSOL® software users who are on-subscription should submit their questions via the Support Center for a more comprehensive response from the Technical Support team.

Suggested Content