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complex relative permittivity: definition of the imaginary part in a look-up table
Posted 02.04.2013, 05:59 GMT-4 Version 4.3a 2 Replies
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Dear all,
I'm quite confused right now as regards the definition of the complex relative permittivity.
In a previous discussion I've read that a complex permittivity of a+jb should be entered as a-jb as COMSOL would always regard the imaginary part as a negative entry.
Now I'm wondering whether this also applies to the definition of the complex permittivity in a lookup table.
Is it either: eps_real(freq)+j*eps_imag(freq) or
eps_real(freq)-j*eps_imag(freq) ?
Thank you!
I'm quite confused right now as regards the definition of the complex relative permittivity.
In a previous discussion I've read that a complex permittivity of a+jb should be entered as a-jb as COMSOL would always regard the imaginary part as a negative entry.
Now I'm wondering whether this also applies to the definition of the complex permittivity in a lookup table.
Is it either: eps_real(freq)+j*eps_imag(freq) or
eps_real(freq)-j*eps_imag(freq) ?
Thank you!
2 Replies Last Post 02.04.2013, 08:47 GMT-4
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Posted:
1 decade ago
Andrea,
it may be best to look at the equations. You can find that in the help pages:
RF Module > The Radio Frequency Branch > Theory for the Electromagnetic Waves Interface > Introducing Losses in the Frequency Domain
Here it states that losses are described with eps_c = eps_0 ( eps' - j eps'')
It appears that COMSOL is using the engineering convention here, whereas the physics convention is eps_c = eps_0 (eps' + j eps'').
I am wondering how often courageous science projects fail because physicists and engineers use different conventions ;-).
Cheers
Edgar
--
Edgar J. Kaiser
www.emphys.com
it may be best to look at the equations. You can find that in the help pages:
RF Module > The Radio Frequency Branch > Theory for the Electromagnetic Waves Interface > Introducing Losses in the Frequency Domain
Here it states that losses are described with eps_c = eps_0 ( eps' - j eps'')
It appears that COMSOL is using the engineering convention here, whereas the physics convention is eps_c = eps_0 (eps' + j eps'').
I am wondering how often courageous science projects fail because physicists and engineers use different conventions ;-).
Cheers
Edgar
--
Edgar J. Kaiser
www.emphys.com
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
Thank you, Sir!