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Metamaterials - Science topic

Metamaterials are artificial materials engineered to have properties that may not be found in nature.
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I am working on lattice structures. I saw in some papers that they used nTopolgy software to achieve the structures' stiffness matrix. unfortunately, I do not have access to this software.
You may guide me from which software or what solution I can get this matrix.
I look forward to your kind reply. Sincerely yours
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You may use the numerical homogenisation method:
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Metasurfaces have been presenting themselves in recent years as promising materials for holography, control of intensity and phase of optical waves, among others; and, in various applications in optics, such as metalens, optical manipulation, 3D image, optical communications and others. What are the advantages (and disadvantages) of holographic metasurfaces in relation to other potential holographic recording medium, such as photorefractive crystals and other photosensitive materials (glasses and polymers)?
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Dear Leon
Thank you for the feedback and for the references.
I'll read the references and post a comment.
Best regards.
Marcos
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I have designed the equivalent circuit of a metamaterial absorber which consists of L, C. S parameter, I got from CST software. Now I want to find out the lumped parameter values. So kindly help me how to find out these parameters value using ADS circuit simulation software?
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It depends on what you are looking for, you can convert S parameters to ABCD parameters in ADS and then use the abcd parameters to get different impedance/admittances of different circuit structures such as pi/t-models.
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I am confused about calculating the absorbability of the metamaterial absorber in between the two formulas below.
A=1-R-T ...............(1)
A=1-R ...............(2)
A=Absorbability
R=Reflection
T=Transmission
calculate the absorbability by equation 1 is mostly published metamaterial absorber paper. But nowadays, other authors comment on these papers.
I also want to design a metamaterial absorber. But which is the formula I use to calculate the absorbability of metamaterial absorbers.
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Equation 1
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Hi,
I have designed a metamaterial structure in HFSS software. I am getting S11 below -10db for certain frequency range, but confused with real and imaginary plot of permitivity,permeability and refcractive index. I am sharing the image of structure and plots. Can anyone help me understand if this structure is behaving metamaterial or not.
Thanks in advance.
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The code for the Matlab extraction is attached to this Paper. Go through it.
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Please let me know how to draw a color plot of PHP propagation of nanomaterials using mathematical tools. Actually, I am unable to draw phonons propagation using COMSOL. Is it possible to find out the plot using Matlab or other tools?
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Definitely, thanks for your kind suggestion
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I want to simulate the developed metamaterial in CST Studio. However, simulation in the Period Structures template does not give me any results. The main aim is to find the permittivity and permeability values from the simulation results. Can someone please tell me what kind of template is appropriate to use and what the settings are?
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Hi
In this link, you can simply learn the method of extracting metamaterial parameters:
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We want to simulate a metamaterial Antenna in HFSS.
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hi
you can use the below addresses for the first time and then modify your metamaterial unit cell structure for your goal:
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Hi !!
During simulation of space coiling up acoustic metamaterial in comsol acoustic-solid structure frequency domain to retrieve the transmission coefficent ,how could we apply floquet boundary condition for a plane wave.
Can someone show me using some numbers or related simulation file ? for better illustration please see the attached file.
Thanks
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Nitish Katiyar Thanks for your reply. I have already referred to the tutorials in the application library specifically "Acoustic Transmission Loss through Periodic Elastic Structures". In this tutorial, they assigned the wavenumber of the incident wave to the Floquet periodicity condition as well. I have based my analysis on this and I am performing a sweep over frequency but, for an x-directional incident wave the ky is getting zero as I am taking ky=k0*sin(theta). This has got me a bit confused.
Are you referring to any specific tutorial? Again, thanks for your reply :)
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Please see attachment, here two terms appeared in the inhomogeneous Helmholtz equation. What is the use of these two terms for a propagating wave in a particular direction.
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Paul Kinsler Thank you sir for your last reply.
This form will be union.
I have one more question . I want to calculate the transmission loss through a structure having a membrane and cavity and supported by an acrylic plate.
I am simulating using comsol multiphysics.
Over membrane I have chosen solid mechanics. The air cavity is assigned pressure acoustics but what about that backing acrylic plate.
I have to assign it as pressure acoustics or solid mechanics.
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Imagine the long-term and almost periodical interaction of gravitation waves with existing distribution of atoms (mostly hydrogen) in deep space. Billions of years of interaction can form a repetitive structure of atoms in huge volume (in 3-Dimesions), with some statistical deviations which can be caused by irregularities of gravitation waves.
Can this repetitive structure (in absence of near source of gravitation) represent some properties of Metamaterials?
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There are virtual particles in vacuum space that we haven't discovered yet experimentally. But this theory proves their existence:
I could verify the existence of detected and hidden particles using teaching about ultimate realities in Abhidhamma.
There is a similarity between the elementary particles (dimensional sets) and Material Forms (Rūpa) mentioned in Abhidhamma.
According to Abhidhamma, there are 28 material forms:
Concretely Produced (Nipphanna)
I. Great Elements (Mahā Bhūta):
1. Pathavi (Extension/Hardness)
2. Apo (Cohesion/Fluidity)
3. Tejo (Heat/Hotness)
4. Vāyo (Motion/Pushing & Supporting)
The above 4 great (Mahā) elements are not the emerged/derived elements. And those four elements made the following 24 elements:
II. Internal (Pasāda) Rupa:
5. Cakkhu (eye element) ==== Photon?
6. Sota (ear element) ==== Z Boson?
7. Ghāna (nose element) ==== W Boson (1)?
8. Jivhā (tongue element) ==== W Boson (2)?
9. Kāya (body element) ==== Gluon?
III. Gocara (Objective) Rupa:
10. Vaṇṇa (visible) ==== Electron?
11. Sadda (Sound) ==== Up Quark?
12. Gandha (Smell) ==== Down Quark (1)?
13. Rasa (Taste) ==== Down Quark (2)?
* Phoṭṭhabba (Tangibility, warmth, and movement) comes
from 3 mahā bhuta of pathavi, tejo, vāyo
IV. Bhava Rupa:
14. Itthi (Feminine) ==== Neutrino (1)?
15. Purisa (Masculine) ==== Neutrino (2)?
V. Hadaya (Mind Base):
16. Hadaya Vatthu (seat of the mind) ==== Z (1/2)?
VI. Life:
17. jīvitindriya (Life faculty) ==== Higgs Boson?
VII. Nutritional:
18. Oja (Nutriment) ==== Magnetic Monopole?
Abstract (Anipphanna) Rupa
VIII. Limiting Phenomenon:
19. Ākāsa dhātu (space element)
IX. Communicating (Viññatti) Rupa:
20. Kāya Viññatti ==== AXion (A)?
21. Vaci Viññatti ==== AXion (X)?
X. Mutable (Vikāra) Rupa:
22. Lahutā (lightness)
23. Mudutā (Elasticity)
24. Kammaññatā (weildiness)
XI. Material Qualities (Lakkhana Rupa):
25. Upacaya (production)
26. Santati (continuity)
27. Jaratā (Decay)
28. Aniccatā (Dissolving)
There is a mathematical way to derive the detected elementary particles and the hidden particles. Please consider reading my book on Binary Mathematical Physics and Buddhism to learn more about dimensional sets.
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Hello.
I try to design metamaterials consisting of a split-ring resonator (SRR) to manipulate its polarization.
To estimate polarization control of the metamaterials for any given incident waves, Jones matrix needs to be obtained, which is a matrix related to input/output electric fields in X and Y axis.
Using HFSS, I designed a SRR where two Floquet ports are located at top and bottom of the SRR and master/slave boundaries surround the SRR.
After running the simulation, I can plot S-parameters for several combinations of ports and excitation modes (TE and TM modes).
But, I couldn't find the ratio of transmitted and incident electric fields in X and Y axis which is necessary to identify the polarization states.
Please, let me know how to simulate E-field transmission coefficient of metamaterials using HFSS.
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Hi there,
HFSS is a complete 3D electromagnetic solver, so the direct result is a vector EM field inside your model volume. There is an internal field calculator where you can define the expression you need (for example, ScalarY(Vector_E) ) and perform basic math operations on points, lines, planes, or subvolumes. Basically, if you know the definition of your "ratio", you can calculate it from scratch.
Regards,
Andrei
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which is efficient model to generate band gaps for acoustic meta materials
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The following RG link is also very useful:
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Hi all,
Looking at the wikipedia page for photonic crystals, there is a section that reads:
"One-dimensional photonic crystals can include layers of non-linear optical materials in which the non-linear behaviour is accentuated due to field enhancement at wavelengths near a so-called degenerate band edge. This field enhancement (in terms of intensity) can reach N^2 where N is the total number of layers"
Can anybody explain this effect? Is there a field enhancement if a 1D photonic crystal is made of two materials with arbitrary permittivities, eps1 and eps2?
Does the enhancement happen without the non-linear permittivity? All materials will exhibit some natural non-linearity, if you drive them hard enough, right?
Or is the magic due to something with this 'degenerate band edge'? Can someone expand on degenerate band edge?
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This is not so mysterious. This is an interference phenomenon. The easiest illustration is probably an etalon. Suppose you have an etalon where each surface has 50% transmission. A beam with intensity I is incident. In the first pass through the material the intensity is I/2. Half of that reflects at the second surface and bounces back to the first surface. There half of that bounces again and continues in the original direction. The intensity of this second pass is I/8. Each subsequent pass is 4X smaller. So, the whole sequence is
I/2 + I/8 + I/32 + etc. However, remember that the field strength is the square root of the intensity. So, the fields add up as sqrt(1/2) + sqrt(1/8) + sqrt(1/32) etc. Adding up those first three terms, you see that the electric field is now up to 1.23! So, if you have a nonlinear phenomenon which is proportional to E^2 or higher, you actually can get enhancement in some parts of the interference pattern. In the case of the etalon the place where you get the enhancement is only inside the etalon. As for being at a degenerate band edge, they are talking about the places where the waves interfere constructively. In the example of an etalon, this happens only if the etalon is the right thickness: t = N * lambda/(2*n) where n is the index of refraction. It's a degenerate band edge in that you can see the behavior repeats at any integer multiple lambda/2. All those choices are degenerate, i.e., do the same thing, and in between you have a repeating range of behaviors (a band) that culminates at the places where the behavior starts over (the edge of the band)
This sort of behavior is very common in all sorts of interference phenomena. Different paths add up in constructive interference and you get a crest with amplitude higher than the contributing pieces. The enhancement isn't magic in that the enhancement comes from adding up pieces that come from somewhere. In the case of the etalon you are adding up parts of the beam that are distinct in time. In other constructive interference you might be adding up pieces of the incoming beam that were distinct in space and laying them over each other. Every bright spot comes with a similarly dark spot because you can't get something for nothing. However, in the case of non-linear optics where you care about the field strength rather than the intensity, clever design can produce dramatic enhancement.
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Hi,
I am trying to plot the dispersion diagram for a transmission line metamaterial IFA antenna, consisting of a capacitor in series and an inductor in parallel to the antenna.
As far as I know, the dispersion diagram is the plot of frequency vs. phase of S21, as phase (theta) is beta*length.
But how to plot the dispersion diagram of an antenna which has only one port?
Kindly help me!
With Regards,
Suhas D
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Thank you Madam Aparna Sathya Murthy and Sir Stuart Barth for your help.
I was going through a paper titled "Small Antennas Based on CRLH Structures: Concept, Design, and Applications."
In this paper the authors have come up with the dispersion diagram of a 3 cell metamaterial antenna (please find attached the image). But I don't understand how they got it. This is the kind of dispersion diagram I need for my metamaterial IFA antenna to observe the Right Handed and Left Handed regions.
Any ideas? Please do help!
With Regards,
Suhas D
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I have a metamaterial absorber structure consisting of several metal-dielectric-metal layers, I have drawn the electric and magnetic field distribution between every two layers.
I want to get the value of the electric and magnetic fields, to calculate the amount of power entering each layer. Note that I am using the Lumerical program (FDTD).
Is there a code or a script for an E, H, and power calculation?
Thanks.
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Farooq Abdulghafoor Khaleel, thank you.
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I plotted the field strengths of the metamaterial absorber layers, and these values are shown to me on the right of the figure. What do these values represent? If it represents the strength of the field, isn't this value too large?
The values that are shown on the right of the graph, what represent?
what do you mean? What is its unit?
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Saad Zahraw Sekhi You are welcome
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I can not extract the material properties of a structure from the CST studio suite. Whenever I set the effective thickness of the material to the Substrate thickness, I get a template-based post-processing error (See the attached Screenshot). What is the reason for it? What does it mean by "effective thickness of the material"? Does it mean the substrate thickness? Please help me extract the material properties with CST. Any suggestions will be gladly appreciated.
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at S11 select S-parameter\SZmax(1)Zmax(1)
and at S21 select S-parameter\SZmax(2)Zmax(1)
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Metamaterials can have exotic material properties. I have come across some metamaterial papers in which the effective permeability or permittivity can be negative. Is it possible to possess positive effective permeability or permittivity by any metamaterial design?
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This answer is copied from the wikipedia:https://en.wikipedia.org/wiki/Metamaterial,
Double positive medium[edit]
Double positive mediums (DPS) do occur in nature, such as naturally occurring dielectrics. Permittivity and magnetic permeability are both positive and wave propagation is in the forward direction. Artificial materials have been fabricated which combine DPS, ENG and MNG properties.[3][16]
To get ref. 3 and 16 refer to the link.
Best wishes
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How to design and analyse metamaterial unit cell...
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Vivek Prakash Yadav i do feel that the Design and Analysis of Two Novel Metamaterial Unit Cell for Antenna Engineering needs to be looked at and the link I have shared here with gives u a perfect picture about the same and hope this is useful to you
One more similar paper publication I came across ResearchGate related to Evaluation of metamaterial unit cell analysis techniques and this is in line with your query as well
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to design antenna with metamaterial
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you can use Lumerical software simulation (FDTD) too.
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i am doing work in acoustic metamaterial and i have no idea how to do simulation . thats why i want to know simulation of a sonic crystal in brifely
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you can see the following link:
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Hello all,
I am working on metramaterial these days,, and I got confused about Negative phase velocity and positive group velocity in metamaterials. I know how to obtain the equations but I can't understand how a wave can have Negative phase velocity (the direction of the wave), but the power propagates in the opposite direction. How would it be possible?
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You better read:
V.G. Veselago. ‘‘The electrodynamics of Substances with Simultaneously Negative Values of Img Align= Absmiddle Alt= ϵ Eps/Img and μ.’’ Physics-Uspekhi, vol. 10, pp. 509-514, 1968.
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There are so many papers where they select different materials for forming metamaterial also use different substrates as well as liquids that evaporate. What interests me most is which materials show the best result to form metamaterials that can be used for nanoantennas. Thus I want to know what to select for forming metamaterials.
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I found on comsol database one online webinar/workshop where a terahertz metamaterial was modeled and there, input "(px*py/4/2/Z0_const)*E0^2" this equation is used. I need to know why is this used?
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There are so many papers where they select different methods for forming metamaterial. In some papers, they used AC sources in others DNA origami and so on. What interests me most is which exact equations show the result to form metamaterials. Thus I want to know what to select for forming metamaterials.
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Fatematuz Zahura are you referring to the physical properties of the metamaterial (e.g., its shape), or the modal properties of the metamaterial (e.g., its dispersion)? While the two are related, generally one of these two is chosen to begin the design with.
Possibly the most simple are transmission-line metamaterials (https://www.waves.utoronto.ca/prof/gelefth/Eleftheriades_Materials_Today_March2009.pdf) -- which can produce very exacting equations -- but are of course simply modelled and are fundamentally just abstractions of physical systems.
On the other hand, complex structures such as your DNA origami can be simulated to a high degree of accuracy, but because they are so complex, it is virtually impossible to find any generalized expression for their behavior.
Somewhere in between is a region where approximate expressions produce reasonably accurate modal results for generalized structures. For example, regular defects made in any material will tend to suppress the propagation of energy when the wavelength of the energy is around one-quarter wavelength in the material.
Selection, I think, should really start with the specifics of your application.
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Any reflective surface of the dielectric material increases the gain of patch antenna, but when metamaterial is used as a superstrate layer on the patch antenna why the gain is improved more? What is the difference between any reflective surface and metasurface in the case of patch antenna?
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A metamaterial is not just, or perhaps not even, a reflective surface. It can have lots of special properties, like having equal phase across its surface, which would increase gain considerably.
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In the comsol simulation of the elastic wave metasurface, what module is used? How is the incident field of a periodic unit set (boundary load/specified displacement)?
And for example, when the longitudinal wave is incident, how to integrate the amplitude (p0, p1, p-1, s0, s1, s-1) of each diffraction order of the longitudinal wave/transverse wave?
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There are two different modules you can use to simulate the propagation of the elastic waves:
1- Acoustic module > elastic wave.
2- Structural mechanics.
However, the solution output of these two modules is not totally the same. for instance, if you want to calculate the acceleration then you have to use the Structural mechanic module as this value is not available in the Acoustic module.
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Greetings to everyone,
Can anyone please tell me which parameters settings are used in a simulation of metamaterial and metasurface unit cells in CST? (Background, boundaries, global properties, etc. )
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Please check this reference
It provides a MATLAB code to extract the permeability and permittivity plots from S-parameters.
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for a Perfect metamaterial absorber how we can find Absorptivity with different angles of ring rotations in HFSS software?
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I assume you're running a two-port Floquet simulation of the unit cell. You can find the relative power lost/absorbed from the S-parameters as follows:
relative power lost/absorbed = 1- |S11|^2 - |S21|^2
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I want to simulate this using the Acoustic structure interaction module.
For ease this can be done by taking a single unit.
How can I do this in comsol?
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Dear Nitish Katiyar
I suggest "scatterer on substrate" mph file availbe both in COMSOL website and applican builder within the software.
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Is there any open source code (C, C++, Python or Matlab) for discrete dipole approximation for scattering problems in a complex dielectric medium ?
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Indeed, if you have a complicated environment around a finite particle, than your best choice is a direct discretization of a large chunk of this environment (with any DDA code, like DDSCAT or ADDA).
The only available option to avoid this is for a semi-infinite substrate - ADDA can account for it analytically (discretizing only the scatterer itself). See https://github.com/adda-team/adda and the paper
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I am looking for the latest approaches to find the band-gap of Phononic / Periodic materials. In this regard, if anyone knows a reference (in detail) for Finite Difference Time Domain (FDTD) theory along with the Bloch method, please share.
I really appreciate any help you can provide.
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For arbitrary unit cells, your best bet is an eigenmode simulation. Sweep the Bloch phase shifts across the various axes from 0 to pi and solve for the eigenfrequencies. The regions in which there are no found eigenfrequencies are your band gaps.
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Does the wavelength the unique criteria to choose the size of unit cells in metamaterial regime ? particularly for microwave applications.
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Instead of asking the physical dimension, it would be more accurate to know the electrical length of the unit cell. We have to use the trial error method always for a certain limiting error. For example, if Lamda/10 does not give correct results in FDM or FDTD, etc numerical technique, we refine the mesh. if we het the results within lamda/5 meshing, we use it.
The length (electrical) of the unit cell depends on the area on application.
1. if you are using within metallic waveguide, much smaller than the conventional substrate based metamaterial. The final results depend on the bending of electric/magnetic fields and its total length (electric/magnetic).
2. Similarly, we are designing a metamaterial using a substrate, please, use the trial error method to generate a suitable electric length to achieve your results. With my limited knowledge, it is found from the published research articles, if we are working upto 18 or 20 GHz, the physical dimensions of the unit cell is approximately 7-10mm depending on application. Form example, at 18GHz, lamda = 16.67mm. Lamda / 4 = 4.17mm.
But, the physical dimension is 7.5mm X 7.5mm or 10mm X 10mm.
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I have designed an antenna whose gain I want to increase,pls suggest how to see which metamaterial will fit in
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Usually the resonant frequency of the metamaterial unit cell is selected same as that of patch antenna. However it must consider the parameters like pass band, stop band, miniaturization factor etc. For gain enhancement applications you can use High Impedance Surfaces. Software optimization also helps to arrive at optimum dimensions.
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I see professional advice to help to attenuate a highly directional interference.
We have a large (~3m) satellite dish antenna for collecting earth observation data. This antenna rotates to scan the sky and works in an 8 GHz band. Unfortunately, a point to point wireless link interferes with the reception during certain hours, and we cannot shut them down due to difficult legal processes.
We have built a metallic wire mesh screen, but it seems to have only a low effect (maybe because of mesh cell size or overall size ... but we are unfortunately limited due to the wind load).
We are considering using frequency selecting structures (FSS) or metamaterials/metasurface to create "negative gain" and thus attenuate the waves coming from the specific direction of the interferer.
Would you mind suggesting some good references to assist with designing such a low-wind-load structure, or perhaps better ideas?
With thanks,
Albert Lysko
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Dear Colleague,
hope this will help
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Dear all,
I recently meet a problem when I use RCWA codes.
In the same structure, it tooks fewer time when using the FDTD solution.
I need set a lot of orders to calcuate the structure which can reach the similar result.
So I have a question that how can I judge the accuracy of the simulation when I use RCWA codes? and How to judge the orders I need?
Thanks
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Sai Chen I am writing the code with matalb, base on Rumpf's lecture. first step. I just consider the normal insert. But very bad news, I the calculate the inverse matrix, no matter inv, ^(-1), pinv,it can not give the right results. And when the harmonics become large (such 40), it give a lot of warning, It seem it is the problem of calculate the inverse matrix. Thank you, do you know why? And the code I write is very short. Less than 200 lines.
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I am trying to simulate THz metamaterials in CST Microwave studio where the transmission needs to be studied with varied amplitude of the excitation signal and the field confinement in my structure in each case. Would highly appreciate your suggestions on this...
TIA.
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I don't know how to do it. This white paper from CST indicates that it is possible. Probably there is more available on the web and in the help.
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I am currently trying to simulate a THz metastructure in CST studio using the frequency domain solver. I would like to know if it possible to change the field strength of the incident radiation. TIA.
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Jihong Zhang Thank you for the answer.The material I am trying to simulate is non-linear in nature, the optical constants are strongly dependent on the field. Which is why I want to alter the excitation strength. I found out that one can feed a custom input signal from the new signal tab under the simulation tab.
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1. How to assign waveport when top conductive pattern (patch) is smaller than the substrate size? Any reference from where the details can be seen ?
2. Master/slave boundary and waveport excitation are not compatible either in this scenario. Without assigning master/slave boundary conditions, can we get accurate dispersion diagram?
3. Unit cell analysis of a linear array (extending only in one dimension) is required. I have found "Unit cell analysis of a Two-D array (for instance, EBG structure)" but in that case port assignment is a totally different scenario.
I don't want to assign Floquet Port on top/bottom of the air box.
Unable to understand the slide number 3 mentioned in the picture.
Thanks for any help!
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You can use the boundary condition (BC). However, your EBG unit cell connected with Vias or not?
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Greetings to all!
How does metamaterial affect antenna Gain and Bandwidth? What are the physics behind them.
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A resonant antenna is a resonant circuit, a metamaterial is also a resonant circuit. Coupled resonant circuits can have useful properties, like increased bandwidth. Look up coupled resonators, double tuned filters, for instance.
Some of the radiation from a patch, for instance, is from the ground. Metamaterials radiate differently to a conducting ground, and can give increased gain in some directions, by reducing radiation parallel to the ground, for instance, or increasing the radiating aperture.
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I have designed a split ring resonator with a metal ground so my S21 is zero. How can I plot the permittivity and permeability and impedance in HFSS?
Since I have used metal ground I also can't find the phase of S21.
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See this article
INVESTIGATION OF EFFECTIVE PERMITTIVITY AND PERMEABILITY FOR A NOVEL V-SHAPED METAMATERIAL USING SIMULATED S-PARAMETERS
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Hi,
I'm trying to simulate a split ring metamaterial from this paper ' - μ Compact magnetic metamaterial lens for 0.35-T MRI' by Hassan Ali et al 2017 in CST Microwave Studio but I'm unable to achieve any resonance in the expected frequency of around 14.88 MHz. I'm unable to get any resonant behaviour in the megahertz range at all. Could anyone check to see if I'm setting up my simulation correctly?
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Great
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Hi Community!
I want a detailed answer or document in which I got to know how you can design a unit cell of metamaterial for a particular frequency and how to bring periodicity to the structure. I have searched a lot but couldn't find an appropriate answer. If someone has the document related to it or had experience in it then kindly help me out.
Thank you!
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I have already simulated the design and of course I get absorption rate as 99.91%. how can i calculate the impedance vs frequency for absorber in cst?
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Yes it has normalized impedance, but i want to know how can i get this normalized impedance in CST.
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If in the antenna design only one SRR structure is used, so can it be also called as Metamaterial based antenna, any literature suggestions for such type of antenna structures.
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A transmission line can be made from a network of series inductors and shunt capacitors. Calling one SSR structure a metamaterial is like calling one inductor and one capacitor a transmission line.
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Dear Sir/ ma'am
When I am doing a simulation of a unit cell of metamaterial in CST, I am getting a warning "mesh adaption termination because of maximum passes is reached". What is it and how much it affects the simulation and to avoid it. I reduced the frequency range from 4 GHz to 1GHz but still, I am getting the same warning. Below I have attached the image of the warning.
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Thank you, Sir, for your valuable suggestion. Can you tell, how to avoid it or solve it?
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What's the application of metamaterial with respect to acoustic propagation in engineering?
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Dear Yunya Liu in addition to Masoud Mohammadi I would like to add that you can use metamaterials for changing the flow of sound, for instance to change the direction of propagation of the acustic wave, furthermore you can use metamaterials for basically the same kind of operations that with ligh, expliting the beam, wavefront shaping etc.
Hope it helps.
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My design contains three parts.
A silicon rubber membrane is placed between upper and lower part.
I want to calculate sound transmission loss by using comsol Multiphysic.
There are lots of module inside Acoustic section.
Which module will be suitable for this??
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Please consider this publication: An analytical model for broadband sound transmission loss of a finite single leaf wall using a metamaterial: DOI: 10.1121/10.0000923. The main model is there is analytical, but verifications is done with COMSOL.
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Hello Dear Researchers,
Is there any guidelines or mathematical formulas (or any reference) on how to calculate the dimensions of the unit cell for metamaterials, metasurfaces or Artificial Magnetic Conductor applied to Antennas or Filters ?
Thank you in advance for your assistance...
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You can probably make the cells a little bigger than 0.1 wavelength, depending on the type of cells and application, but Vadym Slyusar is basically right. It is similar to mesh rules for electromagnetic modelling, you are replacing smooth space with discrete lumped space.
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I designed a 3x3 metamaterial resonating at 28GHz, the return loss is fine but the gain is negative. How can I improve it and also are there any applications of negative gain?
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Can I assume you that your metamaterial was powered/active, and were hoping that it would actually have gain? If so, then I suppose interesting questions would be (a) how much of the natural loss of an unpowered version have you alleviated, and (b) how controllable is that loss compensation?
There is a lot of work on PT symmetric metamaterials, comprising two (or more) segments which have losses in one part, carefully matched with gain in the other. Perhaps even if your unsuccessful attempt at generating gain cannot be improved on, a variable loss version might possibly still have some utility; although this seems to me to be most likely be a rather optimistic view.
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Dear sir/ma'am
I have designed a metamaterial absorber(MA) with a bandwidth of 2GHz w.r.t. 50% i.e. at the full width of half maximum in X-band. My question is whether the bandwidth of a MA is accepted at this value now?
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Dear Punyatoya Routray,
The bandwidth will be acceptable or not depending on the intended application.
Best regards,
Miguel
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Absorption vs Wavelength Plot w.r.to Temperature.
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For this purpose, after simulation, go to the Post-processing template, then
in General result choose '' Optical '' in the first tab and for the second tab choose
'' Calculate Reflectance Transmittance and Absorbance '' then specify Ports and Modes have been used in your simulation and finally click on evaluate.
Done,
Good luck,
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All artificial metamaterials have a periodic arrangement of cells or pieces of metamaterial with a period or several periods that are small compared to the wavelength.
Can there be metamaterials with a non-periodic structure?
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Yes they can. The area of artificial materials is of course an interesting area of research over 100 years old, essentially your question is one related to homogenisation, if your unit-cell is much smaller than a wavelength your system can be considered homogenised and hence can be described via effective media theory's and described in terms of an effective permittivity and permeability. I would suggest for background looking at Maxwell-Garnett and the Bruggeman approach effective media theory's. Lakhtakia presents a comprehensive review of the early work on effective media theories, and a review of more modern work can be found in the paper by Belov that also discusses the homogenisation of metamaterials including a radiation term.
Selected Papers on Linear Optical Composite Materials, Lakhtakia, A. (Ed.) 1996, SPIE Press
Belov, P. and Simovski,C, Phys. Rev. E, 73 (2005)
D. A. G. Bruggeman, Annalen Der Physik, 24, 1935
J. C. Garnett, Phil Trans R Soc Lond, 203, 1904
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1) Series capacitance and shunt inductance provide left hand (LH) behavior. Two mushroom patches gap-coupled with each other, to realize a CRLH TL zeroth order resonator. A single patch is unable to provide series capacitance so Number of unit cells (N) is not equal to 1. Am I right? In this case what would be the correct "Number of unit cells"?
According to my understand N = 1.5, because one patch antenna contributes whereas the series capacitance is shared with the second patch, so can we consider it as 1.5 cells?
2) How can I obtain dispersion graph of such a structure?
Periodic boundary conditions (PBC) are applied on a single element (unit cell) and infinite elements are taken into account to get dispersion graph, or bloch impedance etc. When I considered a single mushroom patch, and apply periodic boundary conditions (PBC) in HFSS, the resonance frequency values on dispersion diagram (beta vs frequency) are not correct. As expected, considering a single patch means we are ignoring the series capacitance which otherwise exists between two patches.
How can we apply periodic boundary conditions (PBC) on two gap-coupled patches?
3) What is the fundamental part/phenomenon of circuit which gives rise to multiple modes in a mushroom structure? I am talking about non-zeroth order modes.
Do the higher order modes (1st, 2nd, -1st, -2nd etc) always exist unless otherwise suppressed by applying some techniques?
Is it just a matter of representation that we select/show only a small portion of frequency spectrum (owing to desired frequency band/area of interest)?
Thanks in advance!
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Bilawal .. A lot of good questions.
1) You're correct; if there's only one patch, the series gap capacitance of course does not exist. In this case, there is no "correct" number of unit cells -- you need a different model. While I've shown in some of my previous work that one unit cell can provide responses similar to those predicted by a periodic analysis, this is not always the case -- it depends on the structure. Two unit cells should give a response in reasonable agreement with the periodic circuit analysis -- though is there a reason you want to define 'N'? I would simply say there are two patches.
2) It's better to say that two unit cells do not sufficiently behave similarly to an infinite array. It sounds like your periodic simulation is correct. It's well understood that there will always be some deviation between the response of an infinite cascade, and a finite number of cells. I don't see a reason why you would want to augment your periodic analysis to match the finite case.
3) Are you talking about resonant cavity (Fabry-Perot) modes? These are simply the modes for which there are multiples of 180degrees existing across the length of your structure, or (180degrees/N)*n, where n is an integer. You can read these frequencies off of your dispersion diagram -- e.g., if there are three cells, the frequencies at which Bd = 60, 120, 180 degrees. Yes, these modes should always exist, although they may each have their own ease of excitation. Generally, we are not interested in all of these -- so only a few may be shown, yes.
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Dear sir/ ma'am
I am designing a metamaterial absorber based on a split ring resonator. Now I want to design its equivalent circuit in terms of R, L, C and want to calculate its R, L, C value. Can anyone suggest the books, or NPTL video or any lecture videos, or paper,s, etc. to get the fundamental idea about equivalent circuits?
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Many fundamentals can be found from books and journals of Christophe Caloz et.al
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How to convert solar energy to electrical in solar cells for Metamaterials nanostructure? what is the principle of operation? How we connect wires to the cells to output the energy?
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Metamaterials are used in conjunction with solar cells to enhance the the delivery of the incident solar radiation to the semicondcutor absorber layer of the solar cells. It can also made to prevent the escape from the solar cell back without absorbing in the active layer. It can help also to link the incident light radiation to increase their path in the thin film materials.
The metamaterial is deposited or structured in the native material with nanodimensions and so they are extremely thin but may be very useful.
Such materials are made from dielectric materials.
In summary they are used to enhance the solar cells by improving their optics.
For more information please refer to the review paper:
Best wishes
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I have been trying to model elastic metamaterials in COMSOL with periodic condition (& floquet theory). While I have been successful with the 2D case, in 3D model of the same structure, I just don't get a bandgap. I have applied the same boundary condition on the same opposing faces (edges in 2D & surface in 3D) in the x-axis. I have attached the 2D & 3D models with their respective Dispersion plots.
I don't understand as to what the issue is here.
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Well, you have a 2D model which I assume is plane strain(?) with some implicit thickness. It would seem that your 3D model is not a good representation of your 2D model, or the other way around.
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I am using copper plate at the back side of my design. And I vary the length of air box (which is used to assign master/slave boundaries and for incidence of wave through floquet port) at the back side of absorber. Because of the copper plate at the back side, absorptivity should not vary even though length of air box at the back side had been changed. But it is varying, why? 
I am also attaching the HFSS files,  go through it
Can anyone help me?       Thanks in Advance.
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could someone tell me how to do floquet port defining to find s11 and s21, as I am beginner to this hfss, and also mention best version of the software?
Thank you
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I need details description about metamaterials simulation On CST MWS.
Also please refer some fundamental books regarding metamaterials absorber.
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Md Mohiuddin Soliman As you are my student, please stay connected for a session on it by Mr. Saif Hannan. It will be this month inshaAllaah.
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Is there any specific website for getting permission to use images and contents of paper of journal, for writing a review paper?
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You have to take permission from the publisher.
Best wishes
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im working now on TPV solar cells and metamaterials and i realy need our help in CST microwave i have a tpv cell simulation and i want to extract particullarly the absorbtion of only the active layer ( cell composed of multiple layers) how i can do that; and also i want to know how to extract the short current density of the cell based on optical properties (basically same question) thanks in advance
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welcome!
You need to know the absorption coefficients of the coefficient of every material in the material stack. You can also get the absorption coefficient given the extinction coefficient. You need to know also the characteristic wave impedance z0 of these materials.
Then you can make ray tracing through this sack where you can calculate the reflectance and the absorbance in each layer.
Knowing the absorbance you can calculate the generation rate of the electro hole pairs. Hence you can get the collected photocurrent from each layer. By summing all these partial photocurrents you can get the overall photo current.
You can proceed similar to the book chapter:
Best wishes
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Can I please ask for good articles/papers/ thesis on Flat Lens Antenna to study? Is it metamaterial or antenna having a metamaterial at the back?
I am looking at this:
Trying to understand what is this?
Thank you
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Hi,
You See Rotman Lens Antenna, it's the same exemple,
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How to calculate the input impedance of patch antenna? How it can be solved in an easy way without using bessel function?
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A starting point to find the input impedance of a patch antenna is:
At resonance; Rin < (1/(2G1)), where:
G1 = (W/(120*lambda0))*(1-((1/24)*(k0*h)^2))
Rin is the input resistance of the antenna at resonance.
This is given in the text book of Antenna Theory by Balanis!
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I am having trouble setting up this problem in HFSS or FEKO. In HFSS, I've tried both FEM and FEBI-IE solvers. With FEKO, I've tried it's MoM solver and default settings. I am would like model model two horn antennas, one in transmit mode and other in receive mode, with a dielectric slab of material in between them. After running the simulations, I'd like to export the s-parameters to apply a material retrieval algorithm like Nicolson-Ross-Weir (NRW) or Newton Raphson to get the permittivity & permeability properties of the dielectric slab.
Link to a paper describing what I'm trying to achieve is below but it was done using CST:
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Hello,
According to your question, I have gone through some papers which I am attaching with it. Kindly go through it, It might be helpful for research.
Thanks,
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Dear all,
Now I'm selecting FEM for design of metamaterials on NIR~VIS frequencies, and keeping 3 software: ANSYS HFSS, COMSOL with wave optics module, and CST STUDIO SUITE.
Could you give me your ideas for these softwares?
I don't mind the price of them.
Sincerely,
Yuta Imade
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I recommend to use Comsol for these reason:
Comsol has both 2D and 3D modeling capability, while in CST you should do some tricks to modeling 2D structures.
Comsol has so powerfull meshing, which is so helpfull in modeling plasmonic structures.
On the other hand CST is so user friend.
Also for modeling infinite lossy substrates, Comsol is recommended.
Hope it help
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Is it possible to get S11 parameter greater than 0 dB in case of metamaterials?
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This is equal or less than 0dB for any passive circuit unless some malfunction in the probe or in the VNA.
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In order to enhance the antenna parameters, meta-material unit cells are added but where to load them is more advantageous either at ground plane or at the patch side, also is it necessary to add them in array or single unit cell can help. The target frequency band is UWB.
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Dear@Praveen,
welcome!
We treated this issue in the paper at the link:
It is like using the parasitic directors in the conventional antennas. They are put in the the front of the antenna in the radiation direction.
Best wishes
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a unit cell of metamaterial has to be analyzed in simulation using hfss. The solution frequency is 10 GHz and range is from 5 to 15 GHz with sweep and interpolating linear step method.
Number of passes are 6 but i am getting these errors -
Discrete solution,process hf3d error:Failure in solving matrix
Solution setup 'setup1',Sweep 'Sweep':Interpolating sweep did not converge.
Simulation completed with execution error on server: Local Machine
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Good question
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Dear all,
I'm looking for theoretical or analytical method to design meta-atom, metasurface, and metamaterials. I only know transmission-line theory.
Would you tell me the good keywords to advance my study?
Sincerely,
Yuta
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Good question
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Hi all,
I hope everyone is doing well and is in good health.
I want to simulate a Honeycomb Core Geometry Sandwich Panel Metamaterial with COMSOL Multiphysics for sound transmission study. It is needed to use beam elements of quadratic geometry order to create the geometry of unit cell. In 2D I do not know how to do that! Do you have any idea about it?
I appreciate your time and consideration.
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Good question
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Hello.
I'm working on transmission metasurface at 60GHz for focusing wave, but I can't simulate full structure by Frequency Domain solver because the error in my system '' is not enough memory'', can you guide me that how to simulate by high accuracy in CST?
my system has 4 core and 32 GB RAM
Thanks, Best Regards.
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