Can CST MWS define eps/mu a negative value?

cst prices define

Can CST MWS define eps/mu a negative value?
why

hfss negative eps

Of course - NOT ! (moreover eps/mu can't be < 1 )
Because eps/mu is a relative values and you can't have inside any materials EM-fields less than nothing

ps. I was to categorical. This is true only for passive media.
In case of active nonlinear media (like a plasma),
where EM-fields can interacts with itself EM-fields of media,
I think it's possible to have such strange effect like negative eps/mu
But it's a very specific cases and the capabilities of MWS, HFSS are out of it...

define eps

Hi, navuho:

The physical materials may not be able to have negative Mu/Eps but synthesized one can and LHM is one of them. This is a very hot topics nowadays. Below is the text extracted from the Internet:

Metamaterial cube (Physics Today, June 2004)
Recent theoretical and experimental results have shown the possibility of creating novel types of micro-structured materials that demonstrate the property of negative refraction. In particular, the composite materials created by arrays of wires and split-ring resonators can possess a negative real part of magnetic permeability and negative dielectric permittivity for microwaves. These materials are referred to as left-handed metamaterials. They were mentioned first as a theoretical curiosity about 35 years ago, but recent experimental demonstrations of such newly-engineered materials have involved the development of new fundamental physical concepts and ideas, also initiating hot debates. A brief overview of this field and a summary of our activities can be found in the recent article (Pdf format, 7 Mb) we published in "The Physicist".


See: **broken link removed** for details.

Actually, I am doing some studies on this topic. But just started the long journey... Hope there are someone who is doing research in this area can be good partners for discussions.

Best regards,

I would like to comment on the ability of HFSS/Finite Element for calculation of composite materials with -ve mu or -ve eps or both; these material is the so-called Metamaterial. In HFSS, a -ve material parameters cannot be assigned, however, HFSS is capable of obtaining or confirming if your model structure is a metamaterial or left-handed material. The analysis if you are familiar is like that of Photonic Band Gap or photonic crystals structure in which unit-cell is setup and subsequently eigenmodes were calculated along the crystal symmetry points.

A paper was published by the Ansoft Technical Team in March 2002 titled "Plane Wave Scattering from Frequency Selective Surfaces by the Finite Element Method." In that paper, right at the end, the authors show how the effective permeability and permittivity of a composite material (split-ring resonator) be calculated by using the finite element method, i.e., HFSS and analytical formulae. In version 8 of HFSS, there is a feature in the Field window called the Field Calculator. This was developed to make our life easier when come to archieve field data in a volume or along a plane. In version 9, users will need to study the HFSS's VB Scripts/Macro manual.

Reference: Bardi, I.; Remski, R.; Perry, D.; Cendes, Z.; Plane wave scattering from frequency-selective surfaces by the finite-element method; IEEE Transactions on Magnetics, Volume: 38 , Issue: 2 , March 2002, Pages:641 - 644.

Here's a paper relating to the subject. Interesting stuff.

**broken link removed**

Regards,
Joe

There is a commercial EM simulation tool that models metamaterials – MEFiSTo (based on TLM)
**broken link removed**
you can see a nice animation there

Dear all:
Why CST cannot deal with negative eps/mu, I think it should not be a problem in re-newing CST code. why not permit a negative eps/mu to anlyze, why just positive value run? Doesn't it just a problem of caculation mathematics?

thank you

jackle

fekete said:

There is a commercial EM simulation tool that models metamaterials – MEFiSTo (based on TLM)
h**p://advancedem.com/mefisto.html
you can see a nice animation there

Click to expand...

This is the first time to hear about this software package. I wonder why they haven't made much publicity, because the packages they produce have many attractive applications. See also their **broken link removed**.

I think there are financial reasons for little publicity. It is mentioned on the site that the price of MEFiSTo is one quarter of the leading competitors price ... Under those conditions it is difficult to compete with the advertising budgets of Ansoft and CST

I am taking this package seriously and believe this is quite a bargain. Sounds affordable for end-user too, other than academic or business type. I am in the progress of requesting for a evaluation. Thank you for your information - Fekete.

In HFSS you can set mu/eps to be negative.

In CST you can not set mu/eps to be negative, but you can set the dispersive Eu and MU!

savedadogs said:

In HFSS you can set mu/eps to be negative.

Click to expand...

Is it realized by taking parameters of a dispersive material at some specific frequency?

you can define Debye parameters to define a metamaterial with disperssive properties.

does a split ring show negative mu? or we must have 2 ring one inside the other .why we must have 2 ring inside each other?

LHM have been studied ever since 1970s. David R. Smith is the first that observed negative refractive index in a experiment where he mount SRR on substrate. Most of software can simulate SRR by simulating single unit structure and perform er/mu retrieval. At certain frequency band (usually narrow), The effective er/mu can appear negative. These phenomena have been studied with tons of research papers. Newest trend is to put metamaterial with non-linear semiconductor devices, which make it behaves even more weird.

https://people.engr.ncsu.edu/dschuri/ECE782_Fall_2009/Topics_files/e016608.pdf this paper describes the retrieval method pretty clear. I can take a look of your code if you want to share it.

sorry how can i share my code here ? i use another paper that seems to be easier . here i only find icon that i can attach picture . i dont know how i can attach a whole article or matlab file !!!

i use equations 16-23 . these are too simple equation i realy dont know where is my falt . do you need s parameters file or my fault is obvious whit out runing program?

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rodgerwxh said:

https://people.engr.ncsu.edu/dschuri/ECE782_Fall_2009/Topics_files/e016608.pdf this paper describes the retrieval method pretty clear. I can take a look of your code if you want to share it.

Click to expand...

i am looking forward for your answer. many thanks