Questions related to Metamaterials
I’m currently in the process of selecting a research topic for my doctoral studies. I have a keen interest in the field of acoustic metamaterials. I would really appreciate if you are helping me to provide your expertise and suggestion to select the topics in the field of acoustic metamaterials
The tutorial or user manuals of OptiFDTD say that it can provide reflectivity and transmission properties of metamaterials as a function of incident wavelengths. However, it seems that it can only provide near-field response of the metamaterial instead of far-field, which can be experimentally observed and useful to know the actual validiy of the metamaterials. There should be physical principle to transfer near-field response to far-field response for such materials. It will be appreciated if anyone tell me some functions in the OptiFDTD available for this purpose.
I am designing a metasurface to control the transmittivity and reflectivity of EM waves at a unit cell level by Floquet simulations. Applying this periodic structure to a large panel leads to a high computational effort. In CST there are methods to homogenize the surface using the scattering parameters, but the dependencies on incidence angle and mode are not applicable in FEM and FDTD solvers. I tried to apply GSTC methods and use an anisotropic effective dielectric material definition, but that did not work for well for oblique incidence.
What is the best way of working to homogenize the panel in CST?
Thank you for your recommendations in advance!
How can I check S11 and S21 of a metamaterial unit cell with respect to various phi and theta angle.
How can I model the red circle part (Paper with 0.24mm thickness and Air with 6mm thickness) in figure1 (equivalent circuit model) in ADS?
Did I do the right job in figure 2(My model in ADS)?
Is there any component in ADS for dielectric layer in certain thickness?
Somebody please help me solve the questions.
Software such as Mirage, Remcom's XFdtd software, OmniSim, etc. exists. but which one is the best for various purposes, for example thermal simulation, acoustic simulation, structural analysis simulation, etc.?
I have designed a metamaterial using FR4 substrate of relative permittivity of 4 for C, X, Ku band applications. Now I want to fabricate it for measurement. When I am sending it fabrication, they are providing the FR4 substrate of relative permittivity of 4 at 1GHz. Will it be constant for other frequency or it will vary?
I simulate a periodic structure placed on a lossy, dispersive half-space whose relative permittivity is smaller than zero at some frequencies. Using CST 2020, I apply open boundary condition (without adding space) in the direction filled with the mentioned medium.
However, the simulation doesn't progress due to the errors. These errors are as follows:
1) "The Floquet port boundary at Zmin must be homogeneously filled with isotropic loss-free and non-dispersive material. For non-dispersive materials, please consider using the option to "Ignore losses" in the solver specials.".
2)"The Floquet port boundary at Zmin has negative material coefficients, which are not supported."
Curious to know the reason. Does it belong to the software limitations or sth?
Any suggestions or ideas are appreciated.
I want to calculate the absorptivity of a metamaterial absorber. But what is the absorptivity formula in the S-parameter in TE and TM mode ???
What is the value of R and T in terms of the S-parameter in TE and TM mode???
Values of R and T:
SZmax(1),Zmax(1), SZmax(2),Zmax(1), SZmin(1),Zmax(1)
SZmax(2),Zmax(2), SZmin(2),Zmax(2).........any other
accurately, i wanna know how to design a transmissive metamaterial cell that produces a wide range of phase differences?
How to use the plane metamaterial lens to realize the function of the dielectric lens (such as convex lens or concave lens), or how to convert the change of the thickness of the dielectric lens into the change of the refractive index of the plane lens, and what is the corresponding relationship between the two
Excuse me I know how to plot the dispersion diagram of a unit cell, but I want to plot the dispersion diagram of a ribbon supercell. Do you use an eigenmode solver? What was your periodic boundary condition? For a unit cell all sides become periodic boundaries, What should it be for a ribbon supercell? Is there any change for phase delays between boundaries with respect to a single unit cell? Best regards
Please share reference is any one has. I am looking in terms of antenna design perspective
I am confused about calculating the absorbability of the metamaterial absorber in between the two formulas below.
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.
I have defined unit cell boundary condition for simulating unit cell of metasurface. If I want to study the reflection phase characteristics of the metasurface then where should be the reference plane in case of floquet port excitation? Should it be coincided at the top layer of the unit cell? Or it should be at Zmax ?
I have studied the literature and found that combining a Helmholtz resonator and membrane results in a negative effective mass density and a negative effective bulk modulus. Typically, in double negative acoustic metamaterials, we find two resonant frequencies, one due to the Helmholtz resonator and one due to the membrane. Is there any possibility that we get only one resonant frequency in double negative acoustic metamaterials?
I would like to know how to simulate the Absorbance of a metamaterial where I vary the Temperature in CST.
Thus, the output of my graph should be Absorbance vs Wavelength/Frequency where the Temperature is varied.
I have observed that some research papers have included ground plane in their design and some have not. What is the purpose of including and removing the ground plane? The ground plane basically reflects the incident wave thus it improves thus the transmission is almost zero in the metamaterial cell. Please help to understand this.
Metamaterials are used in patch antenna as a superstrate increases several antenna parameters like gain, directivity etc. I have read several papers regarding this issue, but couldn't found any proper reason why this parameters are increased? Could you please suggest few papers or explanations based on this issue?
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
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)?
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?
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.
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?
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?
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.
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.
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?
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.
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?
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!
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?
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?
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.
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?
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
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?
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.
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?
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.
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?
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?
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. )
for a Perfect metamaterial absorber how we can find Absorptivity with different angles of ring rotations in HFSS software?
Is there any open source code (C, C++, Python or Matlab) for discrete dipole approximation for scattering problems in a complex dielectric medium ?
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.
Does the wavelength the unique criteria to choose the size of unit cells in metamaterial regime ? particularly for microwave applications.
I have designed an antenna whose gain I want to increase,pls suggest how to see which metamaterial will fit in
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?
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?
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...
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.
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!
Greetings to all!
How does metamaterial affect antenna Gain and Bandwidth? What are the physics behind them.
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.
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?
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.
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?
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.
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.
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??
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...
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?