Frequency dependent Material Definition in HFSS

[maverick09]

hfss material properties dependent on frequency

Hi,

I wanted to know how can we define frequency dependent materials in HFSS and please provide with an example.

Also, where can I find the physics behind definition of these materials.

Thanks

 

[kash787]

material default definition

Hi,

I had the same problem. This is how I tackled it.
When u define a frequency depepndant material it creates a dataset which you can view under projects. You can upload a a *.pts file as a dataset which basically has a number of points i.e. the permittivity versus frequency or loss tangent versus frequency. Once the datasets are uploaded u can create a new material but instead of the standarda numerical values for the permittivity and loss tangent you would write a small definition "pwlx(dataset('file name'),Freq).

What this does is that it tells HFSS to interpolate between the points you have defined which are at specific frequencies. Once you have done this HFSS will try to fit the material properties according to your model and you should be able to simulate your design.

If u need any more help u can send me an email efy8ks@leeds.ac.uk

Hope this helps.
Kash.

 

[sverigeteo]

define permittivity hfss

hey guys,
Interesting topic... I have a problem: HFSS can define the behavior of materials with two different approssimations; but I need that my material behaves in a way that is not fitted by the default options of HFSS...is there any possibility to define this, maybe inserting a certain number of numerical values?
Plaese be clear since I'm a new user of the program... Thanks a lot..

 

[newbie101]

permittivity hfss formulas

Hi All,

May I know the formulas youre using for the material (whatever material) that shows the frequency dependence?

Do you have a formula for ground material? (a general one since ground material could be infinite possibilities)

Please post some of the formulas for other materials too.

thanks,
newbie101

 

[Feri4030]

What is the frequency axis "Scale" in frequency dependent data point wizard? is it GHz?

 

[Feri4030]

Something to know
Frequency scale is in "Hz"
Use "discrete" sweep, interpolating sweep may return inaccurate results WITHOUT warning message

 

[Hasan7]

Re: material default definition

I had the same problem. This is how I tackled it.
When u define a frequency depepndant material it creates a dataset which you can view under projects. You can upload a a *.pts file as a dataset which basically has a number of points i.e. the permittivity versus frequency or loss tangent versus frequency. Once the datasets are uploaded u can create a new material but instead of the standarda numerical values for the permittivity and loss tangent you would write a small definition "pwlx(dataset('file name'),Freq).

What this does is that it tells HFSS to interpolate between the points you have defined which are at specific frequencies. Once you have done this HFSS will try to fit the material properties according to your model and you should be able to simulate your design.

If u need any more help u can send me an email efy8ks@leeds.ac.uk

Hope this helps.
Kash.

Hi,
Thanks your reply is really helpful. I need to ask a question about plasma simulation:
HFSS doesn't accept negative imaginary conductivity. How have you handled that? did you enter the complex permittivity solely(zero loss tangent and conductivity)?

- - - Updated - - -

I had the same problem. This is how I tackled it.
When u define a frequency depepndant material it creates a dataset which you can view under projects. You can upload a a *.pts file as a dataset which basically has a number of points i.e. the permittivity versus frequency or loss tangent versus frequency. Once the datasets are uploaded u can create a new material but instead of the standarda numerical values for the permittivity and loss tangent you would write a small definition "pwlx(dataset('file name'),Freq).

What this does is that it tells HFSS to interpolate between the points you have defined which are at specific frequencies. Once you have done this HFSS will try to fit the material properties according to your model and you should be able to simulate your design.

If u need any more help u can send me an email efy8ks@leeds.ac.uk

Hope this helps.
Kash.

Hi,
Thanks your reply is really helpful. I need to ask a question about plasma simulation:
HFSS doesn't accept negative imaginary conductivity. How have you handled that? did you enter the complex permittivity solely(zero loss tangent and conductivity)?

 

[Quantum Mechanic]

So we can actually input a very large range of functions dependent upon frequency in HFSS. We can use the Drude model for a metal, as an example. Simply place "Freq" in where f (not omega) would show up in your formula.

As for the imaginary parts of the conductivity, this appears as a term in the permittivity. If anyone knows a method to upload equations, that would be fantastic. I prepared a word document outlining this, only to realize I cannot upload it. In the meantime, I can state that since we are using solutions to Maxwell's equations that are of the form E0 * e^(iwt) the complex permittivity and conductivity are the same term, just in different forms; insert that form of the solution into Ampere's law to see.

Finally, an example input to HFSS for this model, using n, e, m and gamma instead of actual numbers,
permittivity: 1-(n*(e^2)/m)/(epsilon_0)/((Freq*2*3.14)^2+(gamma)^2)
conductivity: (gamma)*(n*(e^2)/m)/((Freq*2*3.14)^2+(gamma)^2)

Sorry about any problems with this post; first one.

 

[aptaua]

Helps a lot! I got some inspirations from your reply that we could integrate the imaginary of the conductivity into the permittivity. Thank you!

So we can actually input a very large range of functions dependent upon frequency in HFSS. We can use the Drude model for a metal, as an example. Simply place "Freq" in where f (not omega) would show up in your formula.

As for the imaginary parts of the conductivity, this appears as a term in the permittivity. If anyone knows a method to upload equations, that would be fantastic. I prepared a word document outlining this, only to realize I cannot upload it. In the meantime, I can state that since we are using solutions to Maxwell's equations that are of the form E0 * e^(iwt) the complex permittivity and conductivity are the same term, just in different forms; insert that form of the solution into Ampere's law to see.

Finally, an example input to HFSS for this model, using n, e, m and gamma instead of actual numbers,
permittivity: 1-(n*(e^2)/m)/(epsilon_0)/((Freq*2*3.14)^2+(gamma)^2)
conductivity: (gamma)*(n*(e^2)/m)/((Freq*2*3.14)^2+(gamma)^2)

Sorry about any problems with this post; first one.

 

[electricMac]

Something to know
Frequency scale is in "Hz"
Use "discrete" sweep, interpolating sweep may return inaccurate results WITHOUT warning message

Hello people!
I know this is an old thread, but it is the most relevant to my issue.
I cannot find anywhere (manuals etc) that the scale is Hz. As far as I can understand, when you create the freq. dependent material, if you leave the unit box of frequency as Hz, it will be Hz; but if you make it let's say MHz won't it be MHz when you add the frequency datapoints??