HFSS negative conductivity

[Hasan7]

Hello everyone,
HFSS doesn't accept negative imaginary part for conductivity but there are materials like plasma with a negative imaginary conductivity.I'm assuming that if i defined complex permittivity I could solve the problem.
Does anyone have an idea about this. any reference about plasma or any negative complex conductivity material simulation using hfss ?
Thanks

 

[tallface65]

HFSS does not accept complex conductivities, though they can be entered. Correct representation would be to enter a negative permittivity and a conductivity for a material that exhibits a complex conductivity as a complex conductivity can easily be converted to a complex permittivity using the Lorentz-Drude Model.

given complex permittivity, er = er' + i er", then conductivity = 2*pi*Freq*e0*er" where Freq is the frequency and e0 is permittivity of free space in F/m. the conductivity entered is also just the real part of the complex conductivity.

Hope this helps!

Have Fun

 

[Hasan7]

Very useful indeed.
I wouldn't have heard of Lorentz-Drude model without your help. Thanks a lot.
I'm certainly going to have a deeper look. but for now pardon me to ask about the dielectric loss tangent. it should be (er" + conductivity)/w*er' b but in our case the er'' already depends on the conductivity! and HFSS defines the dielectric constant by er''/er' which is different from the ieee standards.
Can i conclude that i should enter to hfss:
The whole expression of the complex permittivity, the real part of the complex conductivity, zero for dielectric constant?
or should i ignore that er'' depends on the conductivity and enter er''/er' for the dielectric constant