Science topic

Computational Electromagnetics - Science topic

Explore the latest questions and answers in Computational Electromagnetics, and find Computational Electromagnetics experts.
Questions related to Computational Electromagnetics
  • asked a question related to Computational Electromagnetics
Question
1 answer
Hello,
i am conducting some simulations in order to get the Electric field radiated by a cable at a choosen observation point using the electric probe.
As i am using a square signal for the excitation in the time domain, i used the Cosimulation feature of CST.
However, i found out that the results are different from the measurments conducted with the same configuration. The electric field curve has the same shape in function of frequency but the magnitude is different.
I wonder whether it is a meshing problem or a solver problem.
Thanks for your support.
Relevant answer
Answer
Hello,
Few papers are attached.
Thanks,
  • asked a question related to Computational Electromagnetics
Question
5 answers
list of SCI journals that will take low time for responding
( related to MIMO antenna and computational Electromagnetic)
Relevant answer
Answer
Dear Raj,
Unfortunately, most of non-open access journals are not responding fast and they push most of the time to reject. but you can try a relevant journal managed by Springer.
  • asked a question related to Computational Electromagnetics
Question
4 answers
Hello everyone,
I need to know the approximate review time of "The applied computational electromagnetic society". If anyone has any idea, mention it in the comments... Thanks
Relevant answer
Answer
It takes 3 months
  • asked a question related to Computational Electromagnetics
Question
4 answers
Dear Researchers, hopefully someone can help me here:
I built a 2D model in COMSOL, of a simple three-layer covered conductor, surrounded by air.
This cable is for aerial power lines ,
Now, I need to compute the "Dielectric Strenght", this property is given in (V/m) or (kV/mm), of the most outer layer of the Cable.
Does anyone know how to do this in COMSOL ?
Best Regards !
Relevant answer
Answer
Yes, I would like to receive this code. Thanks very much for your general sharing.
Please send to this following email: zhaoliang0526@163.com. Thanks.
  • asked a question related to Computational Electromagnetics
Question
3 answers
Relevant answer
Answer
If you got the answer, please guide me as well Sir, thank you
  • asked a question related to Computational Electromagnetics
Question
7 answers
i have to do some simulations related to vehicle so if any one know about 3D model of car or any other vehicle in hfss so please share with me.
Relevant answer
Answer
Izaz Ali Shah What type of boundary should we assign to body part of a vehicle on which the antenna is being placed.
  • asked a question related to Computational Electromagnetics
Question
3 answers
There is a complicated badly documented object structure in ANSYS EDT (HFSS, Maxwell). It allows many things with scripting, when you know how to access them. But it is a problem, since you usually do not know if the secret knowledge was not passed to you...
So, does anyone know how to get a value of a material property?
Like reading a value of dielectric constant, or an array of BH curve data?
Relevant answer
Answer
BTW, I did not know that direct notation with quotes works!
I usually use the global (project) notation with "$" prefix. Like $eps without quotes. It was required in older versions to use global $parameters in the material editor.
Do you specify your "eps" on the design level?
  • asked a question related to Computational Electromagnetics
Question
3 answers
I was wondering if surface electromagnetic waves can propagate at interface between two dielectrics, both isotropic and homogeneous, but having different relative permittivities.
The literature shows that their characteristics must be different.
Relevant answer
Answer
Yes., there will be propagation of surface waves at the interface between the two dielectrics of the same properties. It is because they will have a different set of characteristics, which arise due to the difference in disturbance of equilibrium of positive and negative charges (Polarization). These displaced charges create an electric field of varying magnitude. It is different from the field produced by the surface wave.
  • asked a question related to Computational Electromagnetics
Question
8 answers
I'm modelling a 3D RVE in ABAQUS and using XFEM to study stationary cracks. I'm facing 2 problems with it. 
1. The above mentioned error:Loading condition might make maincrack under compression.
2. For a mode 1 crack I'm getting comparable values of K1 and K2 from the contour intergrals (I'm considering the 3rd and 4th contours average)
Please help.
Relevant answer
Answer
Hello Sharanya ,
I am doing my project on the topic fracture mechanics. I am also facing similar issue. I have not found any soultion yet. If you already got the solution, could you please share the way to solve it.
Thanks and Regards
Sanjai
  • asked a question related to Computational Electromagnetics
Question
10 answers
Hello everyone,
I'm trying to implement a material with non-diagonal conductivity in my FDTD code. By the way, I'm using Dr. Elsherbeni's code for my purpose. Although I managed to implement diagonal anisotropy in my code, my code seems to be unstable for non-diagonal matrices. Through research, I've found out that my updating equations are not correct. Since it is necessary to interpolate the fields in irrelevant positions, it seems the updating equations also have to be organized differently than the isotropic case.
I attach the equations in a PDF below. the first equation on every page represents the equations in half-steps and the second one represents the updating equations implemented in the code.
Any help or hint would be appreciated.
I also have to point out that the source for the equations is the paper in the link below:
Relevant answer
Answer
Actually the implementation is not that difficult - if you like you can check my lecture notes, pp. 202-203:
  • asked a question related to Computational Electromagnetics
Question
4 answers
I want to know how we can relate magnetostriction with Applied magnetic field mathematically? Or if there is any way to derive it using mechanical equations?
Relevant answer
Answer
There are some classic thermodynamic models to discuss the influence of an external magnetic field on magnetostriction. And we can discuss the influence of external magnetic field on magnetostriction in ferromagnetic materials with different initial stress states.
【1】Shi Pengpeng. One-dimensional magneto-mechanical model for anhysteretic magnetization and magnetostriction in ferromagnetic materials. Journal of Magnetism and Magnetic Materials 2021, 168212. https://doi.org/10.1016/j.jmmm.2021.168212
  • asked a question related to Computational Electromagnetics
Question
7 answers
Hi, I am a student who just started working at a space industry, and I want to know how to teach myself to use HFSS. I have experience with 4NEC2, but HFSS just seems much more complicated, and I was wondering if any experienced people here have tips or manuals to share? My model is a conical shape for cube satellite, at frequency of 2.4 GHz.
Relevant answer
Along with all the great answers above consider the HFSS book for your reference:
Best regards,
Yani
  • asked a question related to Computational Electromagnetics
Question
3 answers
Hi everyone.
I need help about the illustrated result of 1D FDTD simulation. The simulation presents three different lossless media with the following values of relative permittivity and relative permeability, (epsR,muR), (starting from left): (2,2) , (2,1) , (4,1).
The thickness of the layer in the middle is adjusted to give zero reflection at 3 GHz. This sounds fine in the accompanied plot of reflection and transmission coefficients (power coefficients).
The problem is that, although revised many times, I couldn't get unity value for the sum of reflection and transmission coefficients, which indicates a problem in the energy conservation in my simulation. So, what could be that problem?
Relevant answer
Answer
The transmitted field and incident and reflected fields are in different impedance media, so the same electric field represents a different power because the impedance is different. I think the impedance for the reflected fields is the impedance of free space, but the impedance for the transmitted fields is half this, so the transmitted power is probably twice as much as you have calculated.
  • asked a question related to Computational Electromagnetics
Question
8 answers
  • I am characterizing simple cotton textile by using the waveguide method and extracting permittivity from S parameters through Nicolson-Ross-Weir Method. At some frequencies, I am getting peaks on the negative axis side as well. What could be the possible reason of those negative values?
Relevant answer
Answer
That is believable
  • asked a question related to Computational Electromagnetics
Question
3 answers
I have problem with a time-dependent thermal boundary conditions. Is any simple way to implement a time dependent heat flux in Abaqus 6.10?
Relevant answer
Answer
Franco Concli Hi Franco, the link is failed, could you maybe update the link?
  • asked a question related to Computational Electromagnetics
Question
6 answers
Since i am not able to get proper VSWR as well as Return Loss.. at Freq 1.5 ghz.. you can take any number of turns and any radius of helix. please.. I have attached the paper if it can be implemented in CST.. I need it please..
Relevant answer
Answer
You may have the axis too close to your shape or inside your shape, or the pitch is too small so that the helix doesn't miss itself when it goes round in a circle. Start with a small shape a long way from the axis, with the pitch much bigger than the height of the shape and see what it looks like, then make the shape larger or move the axis closer, or reduce the pitch, until you have the shape you want.
  • asked a question related to Computational Electromagnetics
Question
5 answers
I have a closed packed 2D infinite layer of spherical Au nanoparticles. I want to set up a wave-optics (Maxwell's equations) model for it. To reduce the model to a unit cell, I have two choices:
1) A hexagonal unit cell with a nanoparticle in the middle (attachment 1)
2) A rectangular unit cell with 1/4th nanoparticles at each corner and 1 in the middle (attachment 2)
I am solving for the full-field. So for my boundary conditions, I have two ports (top: for excitation, bottom: transmission). To simulate an infinite array, I must implement Floquet periodic boundary conditions. I have done a couple of trials which have not yielded any satisfactory results. So here are some questions, I would like to reach out with:
1) With the hexagonal model, I have set up a simple model with port excitation at the top and PML (perfectly matched layer around), but did not get any useful results. On the otherhand, when I am doing the same for the rectangular domain (without any nanoparticle, just a medium), it works. Is there anything specific that I need to be careful about when I am setting up the unit cell hexagonal?
2) With the rectangular domain, when there is no nanoparticle or when the nanoparticle is in the centre, it works. But when the nanoparticle is positioned close to the walls, the solution becomes unrealistic. I am attaching the two cases. When the nanoparticle is closer than a certain distance from the wall, the solution becomes erroneous. I have read that one has to implement diffraction orders when there are "features" larger than the wavelength. How could I solve this problem?
3) Is anyone experienced with such models would like to share her/his expertise through collaboration?
Thank you for your kind help!
Relevant answer
Answer
Did you used physical controlled mesh? As far as my experience tell me, the physical controlled mesh does note cope well with periodic boundaries, if you get something very close to a periodic boundary the mesh on that boundary will not adapt to the decreased distance and remain coarse. If you are working with square lattice I suggest use PEC and PMC to cut your model into 1/4, but for hex lattice you can try create your own mesh rather than automatic mesh.
  • asked a question related to Computational Electromagnetics
Question
2 answers
I am trying to implement PIC-code for the field emission simulation. According to PIC loop particles injected after calculation of charge density. But I stuck at the problem that at some points of an emitter a field could be accelerative but not strong enough to produce a charge that at least is not lesser than the electron's charge. What should be done in this situation? Macroparticle should not be injected and charge density at these points should be equal to zero or there is some condition that I am missing?
Relevant answer
Answer
If you don't have the condition to inject a full macroparticle at the given point, there is several things that you can do:
1. Gather charge in every step and when the condition is fulfilled (gathered charge >= macroparticle charge) create a particle.
2. Create macroparticle in every step based on some random number, that way in the long run you will have the average value correct.
  • asked a question related to Computational Electromagnetics
Question
21 answers
Recently, I was faced with a new error in MATLAB. It says "Out of memory." I think there should be a way to increase it's memory. Any suggestions?
Relevant answer
Answer
Why are you still using 32 bit?
  • asked a question related to Computational Electromagnetics
Question
5 answers
Recently I’m interested in algorithm about TSCH mode in 802.15.4e, I’m wondering if it’s possible multi-radio mechanism is allowed in communication between motes(or sensors) in wireless network.
Here I treat multi-radio as transmit data on multi channels at the same time to achieve larger throughput, i.e. we can achieve 2Mbps at most at one channel, but with multi-radio, like 5, we can achieve 5*2=10Mbps data rate at most.
I’m not sure if it works, it also seems difficult for antenna design, which is expected to be simple or at low cost.
Relevant answer
Answer
Dear sir it is possible to design with the help of mimo antenna through which many antennas working at the same time to transmit and reception of the signal.
  • asked a question related to Computational Electromagnetics
Question
5 answers
Actually, I'm expecting answer to perform a computational program and its code related concept. 
Relevant answer
Answer
Hey!
I had a query along similar lines though I have been working with the Python meep wrapper for a while now, I keep facing a problem with metallic components say thin films of metal. The field intensity blows up near a metallic film and hence when you run a Meep code for something as simple as calculating the transmittance of the said film the code shows an error because of Inf field intensities.
  • asked a question related to Computational Electromagnetics
Question
3 answers
Hello,
I am trying to reproduce result from one of the published paper. However, no way I get the apparently meaningful result. Can anyone please suggest me what I have done wrong in the design, i.e. port define, boundary,
Every dimension has been taken accurately as per the attached paper. So structure is as accurate as possible. I have uploaded both my hfss design and paper. I am trying to reproduce fig 13(a) and (b).
Help and suggestions will be highly appreciated. Thanks
Relevant answer
Answer
Ansys electronics 19.2. FEBI method has been used for air box which is the most optimized and perfect as per Ansys.
  • asked a question related to Computational Electromagnetics
Question
6 answers
Does anyone know if the poisson solver will enable the calculation of capacitance between electrodes with a cylindrical structure?
Relevant answer
Answer
Thank you to everyone who has replied. Since asking this question, I discovered the MIT FastCap program, which is downloadable as C source code. In my tests, FastCap is found to calculate capacitance with very good accuracy (essential for my purpose). I plan to publish something on this in 2020.
  • asked a question related to Computational Electromagnetics
Question
4 answers
I use CST for simulating EM-pulse propagation through the human's body. For this, I using time field monitors which allows me to calculate SAR distribution on a certain time interval. The pulses have very broad spectra with unequal energy distribution at different frequencies, but CST doesn't support time monitors with dispersive materials, which means I can set only one value for the losses in materials of the human body model, what's incorrect. Is there any software which supports dispersive materials in time-domain 3d EM-simulations?
Relevant answer
Answer
Try gprMax
  • asked a question related to Computational Electromagnetics
Question
58 answers
Einstein, based on his argument in section 6 of 1905 paper, claimed:
“If a unit electric point charge is in motion in an electromagnetic field, the force acting upon it is equal to the electric force which is present at the locality of the charge, and which we ascertain by transformation of the field to a system of co-ordinates at rest relatively to the electrical charge.”
Simply, total electromagnetic forces, acting on a moving charge, claimed to be equal calculated in any inertial reference frame; F’ = F.
Using an example, Feynman, in his lectures, failed to prove that electromagnetic forces are equal if calculated in the two inertial frames suggested by Einstein.
His result was F’ = γ F
Why did Feynman fail? Can you find an example to support Einstein’s claim?
Attached file presents and reviews Feynman’s analysis and calculation.
Relevant answer
Answer
Following such valuable discussion .
  • asked a question related to Computational Electromagnetics
Question
1 answer
Hello,
I am dealing with the development of a new fdtd code using the CFDTD method. Is it correct to multiply the electric field with the franctional lengths in magnetic field update equations or multiply the calculated electric field after the electric field update equations? I think that if we decide to do the aforementioned multiplication both in magnetic field equations and electric update field equations this is equal to multiply by the fractional lengths squared. I have attached the procedure taken out of prof. Gedney's cource of FDTD (found online)
Thank you in advance for the answers
Relevant answer
Answer
I am working on the same problem. can you please send some reference papers on conformal FDTD
  • asked a question related to Computational Electromagnetics
Question
4 answers
in hfss, sweep type is three options are discrete, fast and interpolating. which is better for simulation and what is relation between these sweep , discrete and interpolating.
Relevant answer
Answer
Hi Srinivasa ,
Seyed-Ali Malakooti
The discrete sweep is the most accurate as it resolves the problem at each frequency point in your whole frequency range. However, it is the slowest and the adaptive frequency should be set at the higher limit of your bandwidth or at the frequency where the wavelength is smallest.
Fast Sweep:
The fast sweep requires less simulation time than the discrete sweep but at the expense of a limited frequency bandwidth range and reduced accuracy. The adaptive frequency should be set within the center of your frequency bandwidth and should coincide within the pass-band of your structure. if your adaptive frequency is 10 GHz, your frequency sweep can go from 1 GHz to 20 GHz.
Interpolating Sweep:
The interpolating sweep is the fastest, but the least accurate sweep. In addition, the field data cannot be saved for the frequency range and therefore has limited post processing attributes.
Bests,
Hadi
Seyed-Ali Malakooti
  • asked a question related to Computational Electromagnetics
Question
5 answers
I would like to assign wavegiude port in CST for '' bent antenna design'' but it does not work and this message below appear when I run simulation (Waveguide ports must be aligned with cartesian coordinate planes for the transient solver.) does anyone know how I can deal with that problem and what's the solution for? Thanks in advance.
Relevant answer
Answer
Make your feed line longer and put a bend in it (perhaps the reflection of the bend to the patch) so that the port end is perpendicular to one of the axes.
  • asked a question related to Computational Electromagnetics
Question
3 answers
Hello everyone,
I am searching for references in numerical modelling of fully-coupled electromagnetism with FEM for high frequency applications? I am particularly focussed on induction heating of magnetic polymers with hysteresis losses at high frequency alternating external magnetic fields.
Any help is very much appreciated!
Thank you in advance!
Relevant answer
Answer
Dear. Maybe you can try: Numerical techniques in Electromagnetics. Matthew N. O. Sadiku.
  • asked a question related to Computational Electromagnetics
Question
8 answers
I am trying simulate an infinite domain so I need to use non-reflective boundary conditions. While searching, I came across PML method, but I have certain doubts.
1) How to decide the dimensions of the PML layer?
2) What effect does PML mesh size have on the reflected waves?
I am using TNO DIANA and I simulated a block of soil of 50 m subjected to an impulse load and tried to see the wave travel. I used PML lengths of 10 to 50 m . However, I can still see waves reflecting back. I also tried to increase the function values assigned at the PML boundaries, but after one point I see that the PML behaves like a clamped or fixed boundary. Can someone point me to a source where PML is explained clearly?
Thank you very much.
Relevant answer
Answer
It is not sure which software you will use.Generally, PML requires approximately a thickness of one lamda (largest wavelength). In COMSOL,the PML is available for frequency domain simulation.However, it does not provide PML for transient simulation based on the elastic wave equations.You can refer to my published work.
  • asked a question related to Computational Electromagnetics
Question
1 answer
Hallo,
i am trying to compute the temperature distribution in arc welding simulation by using two heat source simultaneously (first one on the top of the plate and second one on the bottom of the plate). For this simulation i am using the software LS-DYNA. But, unfortunately my simulation terminate with following error which i am unable to understand:
*** Error 60110 (IMP+110)
terminating : MF2 Factorization error 14
E r r o r t e r m i n a t i o n
When i compute the temperature field by using only one heat source then it works perfectly.
can anyone give me some suggestion regadring this error message.
Regards
Braj
Relevant answer
Answer
Dear Sir i am getting the similar error , Can you tell me how you solved Mine error is in-core numeric storg 2 = 5854.91 Mw out-of-core num. storg 2 = 771.24 Mw factor and solve may be out-of-core *** Error 60110 (IMP+110) terminating : MF2 Factorization error 18
  • asked a question related to Computational Electromagnetics
Question
4 answers
I'm trying to carry out a static analysis of a sandwich structure using Abaqus, how can I connect the face sheet and the honeycomb core if the core is modeled in detail?
Relevant answer
Answer
You can give tie constraint between the honeycomb surfaces and the skin. Hope this answer will be helpful. May i know how you modeled the honeycomb?
  • asked a question related to Computational Electromagnetics
Question
5 answers
My present investigation involves simulation of optical interaction of plasmonic nanostructures using COMSOL Multiphysics (frequency domain analysis). To ensure that my results are free from any numerical artefact, I would like to ask some basic questions:
1) How similar are the frequency domain and time domain results (When optical spectra are compared for complex structures)?
2) Should analytical methods like generalized Mie theory, coupled dipole method, etc., in principle, agree well with numerical methods (as my numerical results do not agree well)?
2) Do different nuumerical frameworks like Lumerical, COMSOL Multiphysics, CST Microwave studio, etc., give very similar solutions for complex structures (like for simple structures, they all agree well)?
There is indeed some literature that compares different method for rather simple models. However, as the system gets more complex, one would expect that the uncertainty grows too.
Relevant answer
Answer
Hi Rituraj,
There are two important aspects in modelling, you should always check and be aware of:
(a) What approximations have been made? (e.g. electrostatic limit, local approximation, dipolar approximation, etc.)
(b) What are the convergence criteria of the method that is used? (e.g. meshing, element size, orbital momentum number, reciprocal space vectors, time steps, adaptive methods, etc.)
To point 1)
Mathematically, Maxwell's equations in time and reciprocal (frequency) space are equivalent, and in principle, different methods should yield same results. However, approximations often have to be made in order to obtain equations that allow implementing a feasible numerical framework.
To point 2)
For analytical methods, most likely stronger approximations had to be made. In the electrostatic limit, e.g., retardation effects are neglected, and the method is not suitable for more complex, larger systems.
To point 3)
You are naming comercial software, not numerical methods. Those are - to my knowledge - based on FEM/FTDT. Under similar settings regarding, e.g., meshing and boundary conditions, they should yield similar results. These are suitable for larger and more complex structures with no symmetries, however, convergence is an issue to keep in mind for small gaps, corners/edges etc. and computational time suffers from complex meshing.
which compares different methods and discusses in depth advantages and disadvantages of those methods for gold NPs of complex shapes.
And regarding implementing nanoscale effects beyond classical Maxwell's equations, my own work might help:
All the best,
Christin
  • asked a question related to Computational Electromagnetics
Question
9 answers
HI all,
I was going to loft two different faces but I have been faced with this error:
Lofting Failed: face has more than one loop.
I will be grateful if you help me.
Relevant answer
Answer
I think it has nothing to do with your CST version as I could see
1-you selected a face containing two circles and that's why you get the error saying that the face has more than one loop.
2- you are better to create a horizontal and vertical distance between the prependicular faces in order to prevent it from making single section lofts without sufficient curves.
Try these two points and let me know the result.
  • asked a question related to Computational Electromagnetics
Question
13 answers
I want to obtain dispersion diagram of the periodic structure with CST. The structure is finite in transverse direction: "A row of pins which consists 7 pins laid under a metallic plate. The entire row is laid between two metallic sidewalls. the row of pins together with the sidewalls are repeated along the longitudinal direction periodically". But when I simulate the structure with CST Eigenmode Solver, I obtain two additional modes compared to a paper's result. Can anyone help me with this problem please?
Relevant answer
Answer
Hi
Parinaz Sadri-Moshkenani : I have simulated the dispersion diagram with CST and i get results that is similar to the results in the paper i am simulating.
But i don't know the relation between beta(propagation constant) and phaseY. Can you tell me how these two parameters are related to each other?
I have attached the results for you.
  • asked a question related to Computational Electromagnetics
Question
2 answers
I have access to the electronic charge density for both molecules as well as their quadrupole tensors, both isolated in vacuum and when they are interacting. I suppose it could be possible to compute the field due to one quadrupole and compute the potential energy of the second quadrupole within that field. Is there a convenient way to do this?
Thank you for reading
Best Regards
Relevant answer
Answer
If the molecules have spatial extensions and overlap each other, you have add the contact interaction (eq. 2.2 from the attached article)
Note for Professor Jerrold Franklin: you can compile the Latex file on your own computer, and then use "add file" for the pdf file.
  • asked a question related to Computational Electromagnetics
Question
12 answers
Hi,
I have noticed that FSS unit cell tested inside a waveguide shows a wider bandwidth than a periodic surface of the same unit cell (with exact same cell dimensions) tested in free space.
Apart from the difference in the wave impedance, what could possibly make waveguide have wider S-parameters response?
Thanks..
Relevant answer
Answer
Dear Baraa,
Thank you for sharing the details of your FSS design with us. I assume that the parameters of your periodic FSS structure are those of a square or rectangular lattice? From what I remember about FSS measurements in rectangular waveguide simulators, the lattice of your perodic structure must be at least rectangular in form and you need to place two unit cells side-by-side across the broad dimension of the waveguide. This is to emulate the correct symmetry and periodic boundary conditions of the full lattice. Did you use side-by-side elements in your waveguide simulations and measurements, or just one element? You can think of this two-element arrangement as generating an infinite set of image elements with respect to the side walls of the waveguide. You would be not able to simulate a triangular lattice in a rectangular waveguide, for example. Whilst I would fully expect your computed and measured results to agree well for whatever FSS element you place in the waveguide, the trick in an FSS waveguide measurement is to mimic the actual periodic boundary conditions that occur in a full lattice. If you've only modelled and measured a single FSS element in the waveguide, the results would not pertain to the same lattice parameters of a fully periodic (free-space) structure involving that element. My previous comments about the plane-wave decomposition and frequency-dependent angle of incidence in the waveguide measurement would still apply to the case of two side-by-side elements placed in the waveguide.
Regards,
Ray
  • asked a question related to Computational Electromagnetics
Question
7 answers
The recoil force of radiation is known for spontaneous emission (for the radiation of an accelerating charge or dipole), when the photon field is empty. Is there any difference when stimulated emission is considered? Would it be enough to add an external force to the original radiative reaction-force without changing the original form of the radiative reaction?
Relevant answer
Answer
more precisely:
" The net change regarding momentum and energy exchange with EM field
is identical to SPONTANEOUS emission, isn't it?"
  • asked a question related to Computational Electromagnetics
Question
5 answers
I want to plot the permeability of an SRR using CST "Template based post-processing > Mix template results " based on S11 and S21 as shown in the formula below:
mu = (2 * c (1 - v2)) / 2 * pi * f * d * i (1 + v2).
all parameters are known except f (which is the frequency varying from 0.5 to 3 Ghz).
Is their any variable that represent it in CST? how can we calculate the permeability then ?
Relevant answer
Answer
I figured out just now
Use XAxis function solves the problem. As you can see I have f plotted.
  • asked a question related to Computational Electromagnetics
Question
4 answers
I found a tutorial in HFSS from which we can calculate RCS (dB) with respect to theta and iwavetheta (deg) (for both monostatic and bistatic RCS). With respect to frequency, how we can calculate ? Can any one help me ? If possible upload the HFSS file, it will be easy for me. Thank you
Relevant answer
Answer
Dear Sreenath,
The steps to plot RCS vs Frequency:
  • Set Up Radiation: Insert Far Field Setup --> Phi from 0 to 180 and Set “Step Size” to 10 degree. Also Set Theta from 0 to 360 and step size 1 degree.
  • Results->Create Far Fields Report->Rectangular Plot --> Select “Monostatic RCS” and then “NormMonostaticRCSTotal”. In the Primary sweep Select Freq.
  • Under Families tab select the values of Theta and Phi you want the calculation for.
  • asked a question related to Computational Electromagnetics
Question
17 answers
Dear all,
I have a problem about 'Tie constraint' when I try to model the simple beam in ABAQUS, with warning:
"For *tie pair (assembly_s_surf-4-assembly_m_surf-4), adjusted nodes with very small adjustments were not printed. Specify *preprint,model=yes for complete printout."
In my case, I try to tie two surface of two solid parts, as the picture following. But my model always can not go on because of that erorr.
Do you have any ideas for this problem? Please
Thank you so much!
Relevant answer
Answer
Dear Thuc
To deal with this warning, when creating a job to run follow this path:
Create job > General> Select “Print model definition data”
Though it is not an important warning
To solve the problem with the error, consider the mesh sizes equal for parts and select the object with higher stiffness as master and use the discretization method “surface to surface”.
Best regards
  • asked a question related to Computational Electromagnetics
Question
3 answers
how can we use cst code for cyclotron magnet simulation? is it a realible code for this purpose?
Relevant answer
Answer
CST particle studio is a powerful tools for particle tracking under various electromagnetic forces. This code is a user- friendly useful tool for your application.
Go to the following link:
  • asked a question related to Computational Electromagnetics
Question
21 answers
A vector field that has a curl cannot diverge and a vector field having divergence cannot curl. 
But the curl (rotation about a point) of maximum space rate of increase in a scalar field equals zero? What does this mean?
Relevant answer
Answer
A scalar field is single valued. That means that if you go round in a circle, or any loop, large or small, you end up at the same value that you started at. The curl of the gradient is the integral of the gradient round an infinitesimal loop which is the difference in value between the beginning of the path and the end of the path. In a scalar field there can be no difference, so the curl of the gradient is zero.
  • asked a question related to Computational Electromagnetics
Question
4 answers
I am trying to design a rectangular waveguide (WR12) power divider/combiner to split/combine my signal and at the same time maintain a good isolation between the two fan-out legs.
In my simulation, I have tried a simple T junction with a septum in the middle, it works well as a fan-out and combiner but the isolation is poor.
Does anyone know any design tricks so I can achieve a good isolation while maintaining a good power dividing insertion loss? I can't use isolator structure in my design since my signal will go both way.
Thanks!
Relevant answer
Answer
Hi Smrity,
Thank you very much for your answer and the paper. The SIW paper is very interesting! I could use it for a fanout design in one of our boards.
Best regards,
Wei
  • asked a question related to Computational Electromagnetics
Question
5 answers
Which software is best for finite element method analysis (FEM) to detect the magnetic field using photonic crystal fiber?
Relevant answer
Answer
I think COMSOL Multiphysics software is best for modeling and tracing different optical guiding parameters of PCF.
  • asked a question related to Computational Electromagnetics
Question
3 answers
I think when a random media changes in time in addition to space, the particle at a definite location at the present time is not the same as the past time (it's shape may be changes or may be there is'n any particle there!).
according to these explanations, do you think that FDTD method (that is time based) is an appropriate numerical method to analyze such random media?
or my thoughts are not true and i can apply FDTD method to a random media that changes both in time and space?
Thanks in advance!
Relevant answer
Answer
i found that my problem corresponds to dynamic random media and If i can give a function to express the locations of particles at any time (function of time), the FDTD method still can handle this kind of random media.
  • asked a question related to Computational Electromagnetics
Question
4 answers
I want to simulate a discrete random  media with FDTD method.
the simulation environment is air that is filled with random spherical particles (that are small to the wavelength) with defined size distribution.
what is an efficient  and simple way to create random scatterers in large numbers in FDTD code?
i have put some random scatterers in small area but i have problem producing scatterers in large numbers.
 any tips, experiences and suggestions would be appreciated.
thanks in advance.
Relevant answer
Answer
Paralellizing a code is not easy.  You may want to get a hold of a commercial tool like Lumerical or an open-source tool like Meep if you need parallelization.
It is possible.  You will need to "voxelize" the STL file in order to identify points on the grid that are inside or outside of your particles.  Search Mathworks website for anything called Voxelize or something like that.  There is a little more information about this in Lecture 19 here:
  • asked a question related to Computational Electromagnetics
Question
4 answers
i want to simulate random particles with pre-defined distribution in CST.
these particles are small to the wavelength and the frequency is high (at GHz ranges)
could you please introduce some references or papers that could describe more in details how to create such medium (random particles) in CST?
thanks in advance.
Relevant answer
Answer
Hello,
I m giving link below, kindly follow and apply secondary emission .
Without using this, random particles are not possible.
Thanks,
  • asked a question related to Computational Electromagnetics
Question
8 answers
I want to implement the FDTD method to a discrete random media ( a medium which is filled with discrete scatteres randomly). the scatterers are also small (to the wavelength).
could you please introduce some refrences or papers that applied such method to the mentioned medium?
any tips, suggestion or experiences would be appreciated.
thanks in advance.
Relevant answer
Answer
Dear Fateme,
The following paper describes electromagnetic simulation of randomly distributed particles in a dielectric matrix using CST EM Studio software:
K. A. O'Connor and R. D. Curry, "Three-dimensional electromagnetic modeling of composite dielectric materials," 2011 IEEE Pulsed Power Conference, Chicago, IL, 2011, pp. 274-279.
This paper also compares the computed results with a number of well-known closed-form mixture formulae. In the above paper, you'll see that Lichtenecker's logarithmic formula agrees very closely with the computed values. This formula was originally thought of as a semi-empirical one until I published a derivation of it in my paper of 2010 based on Maxwell's equations and the conservation of charge (citation below):
R. Simpkin, "Derivation of Lichtenecker's Logarithmic Mixture Formula From Maxwell's Equations," in IEEE Transactions on Microwave Theory and Techniques, vol. 58, no. 3, pp. 545-550, March 2010.
In that paper, the derivation of Lichtenecker's logarithmic mixture law is shown to be fundamental for a truly random mixture when the particles are small compared to the wavelength ( ie a quasi-static model).  I also showed in this paper that the Maxwell-Garnett and Bruggemann formulae are approximations to Lichtenecker's logarithmic formula valid for weak coupling between particles.
In implementing a computational model for randomly dispersed particles, I would avoid introducing any kind of periodicity (eg a super-cell approach) since this could introduce spurious band-pass or band-stop behaviour that isn't representative of the actual behaviour of the material being modelled. 
Hope this helps!
  • asked a question related to Computational Electromagnetics
Question
6 answers
Can any one suggest application of microwave absorbers in 5G communication systems?
Relevant answer
Answer
Main application of absorbers is isolation enhancement. They also can be used as filters and attenuators. 
  • asked a question related to Computational Electromagnetics
Question
5 answers
Why the E plane beam width of monopole antenna gets narrow when we increase the width of ground plane of monopole antenna???
Relevant answer
Answer
Thanks so much Mr. Malcolm , Mr Rusan and MR Sudipta 
  • asked a question related to Computational Electromagnetics
Question
4 answers
I want to simulate  random media  filled with discrete scatterers  with an appropriate numerical method.
is it possible to calculate the scattering with S-FDTD or (ordinary )FDTD method? if not what would you recommand to better describe the wave propagation behavior in such medium?
thanks
Relevant answer
Answer
thanks a lot prof.Rumpf for your realy useful suggestion, surely i will do some literature search to find out more infomations and datas to better define and model the medium.
  • asked a question related to Computational Electromagnetics
Question
1 answer
if i want to find the parabolic structure  of the antenna with wire mesh triangular facets how can i apply the the force density method.
Relevant answer
Answer
Do you want to  construct an approximate paraboloid  out of  triangles and need to
calculate the statics of the assembly? if yes, you should probably use Finite Elements
method.
  • asked a question related to Computational Electromagnetics
Question
4 answers
I want to plot the sections c AND d of Fig 3 of attached paper in CST software. would you help me?
Relevant answer
Answer
Hi, Dr. Gudarzi
I didn't have done exactly the performance that you want, but I have an experience may be helps you.
I CST one can make mathematics or logic equations with the obtained results parameters.
for this, use post processing tab -> template based post processing -> select something in upper pop-up ( e.g. 2D and 3D fields) and then select Mix 3D fields (from lower pop-up), So a window will be open in which you can make your own equation like a simple division or summation and so on.
hope this could help.
  • asked a question related to Computational Electromagnetics
Question
4 answers
I am trying to simulate a coupled differential micrsostrip transmission line in CST to obtain the differential impedance. I used two (full plane) waveguide ports to obtain the even mode model, the port mode results I got only contained the wave impedance.
In an attempt to obtain the odd mode, I sliced the model into two halves, as shown in the figure, and used 4 waveguide ports. The s-parameters obtained and the field current did not follow the expectation, as I was getting current at the dielectric (Rogers RO3003). Is there a way I can obtain a line impedance for the structure? I tried the same procedure with a single microstrip and I only obtained the wave impedance.
Relevant answer
Answer
Hi,
Take a look at the attached file. it covers both the issue of correct port definition as well as differential ports.
  • asked a question related to Computational Electromagnetics
Question
2 answers
Hi,
Kindly if someone can let me know that how I can find (BPE) in cst microwave studio  as shown in the attach  figure... I  am not sure operating  this device ?
I  did  try  to find it in cst design studio.... but fail.
Relevant answer
Answer
Hi Mujeeb
Id say the one with a red square might be the 3 dB divisor (3 dB splitter in the attached picture) whereas the one with the small arrow is an ideal phase shifter.
  • asked a question related to Computational Electromagnetics
Question
5 answers
Now a days ,For multiple frequency for different application,we must require frequency reconfigurable antenna.But it is challenging to design .
Relevant answer
Answer
Dear Deepak,
Can you be more precise about your question?
If you want to know just the challenges in designing the frequency reconfigurable antennas, you may refer to this paper: DOI: 10.1109/VTCFall.2012.6399212
Good luck
  • asked a question related to Computational Electromagnetics
Question
3 answers
how to obtain Rcs dBm vs theta in polarization reconfigurable antenna
Relevant answer
Answer
hi Smirity ,
 thank u. i am using cst . when i select farfield option in the farfield results, i dont find how to change theta ,phi for different settings. can u plz clarify
  • asked a question related to Computational Electromagnetics
Question
6 answers
I would like to use XFEM to simulate cracks based on the stress field calculated by the UMAT. Does anyone have an idea about this topic?
Relevant answer
Answer
Hi Jianwei,
According to your previous question, do you got the solution for that?. I have to try to link between UMAT (ductile damage model) with XFEM, but unfortunately, the result from solution dependent variables (SDV) are not really accurate.
I have to try to link between UMAT (ductile damage model) with XFEM, but unfortunately, the result from solution dependent variables (SDV) are not really accurate.
Do you have any experiences before?.
Many thanks.
  • asked a question related to Computational Electromagnetics
Question
1 answer
I am currently using comsol Multiphysics for simulating the optically excited acoustic modes of the microresonator. But I am having a problem with it as I am not able to create a link between optical modes and acoustical dynamics. I have created a successful model for finding optical modes in comsol I just want to extend the same to acoustic modes.
Relevant answer
Answer
I am not familiar with acoustics but I guess you will have some outputs from optics physics which will be used in acoustics physics. so I propose you to see this example with path "Wave_Optics_Module/Optical_Scattering/ scatterer_on_substrate".
I hope it help you.
  • asked a question related to Computational Electromagnetics
Question
8 answers
How can I simulate the graphene in CST?
how can i define it?
please send me a tutorial or help me.
thanks
Relevant answer
Answer
I recommend you to watch this webinar beside the above mentioned valuable papers.
  • asked a question related to Computational Electromagnetics
Question
7 answers
I have already tried the LF low Frequency domain solver. The problem with this solver is that it does not support a bulk media with negative mue value which i need for my research. That's why i need to design a small dimension coil in High Frequency solver.
Relevant answer
Answer
if you calculate dimension for the coil at 65 MHz , it wil be large, u can reduce the dimension by incorporating open stub on it or  any other reduction technique.
  • asked a question related to Computational Electromagnetics
Question
2 answers
build a single slot waveguide antenna, to optimize parameters, length, shift . How to optimize. something wrong
Relevant answer
Answer
Thanks a lot.
  • asked a question related to Computational Electromagnetics
Question
1 answer
I want to calculate the RCS of an arbitrary and symmetrical shape by a numerical method in MATLAB domain and need the mesh centers to the center of the geometry length.
is it possible to model it in CST and import such mesh informations to  MATLAB domain?how?
any experiences and suggestions would be appreciated.
Thanks
Relevant answer
Answer
Hello,
It is possible to collect mesh information from CST for any geometry and to implement that mesh information into MATLAB is likely to possible by taking swarm optimization technique to rectify the structure more and more to get optimized results.
Thanks,
  • asked a question related to Computational Electromagnetics
Question
5 answers
As i haven't use Quarter-wave transformer before i am confused. Your response guys would help me alot.
Relevant answer
Answer
Thank you so so much guys really appreciated. :)
  • asked a question related to Computational Electromagnetics
Question
5 answers
As we all experience this that radio waves  loses its strength while transmitting through environment. That is why we have to Amplify the signal before and after processing it.Do you have any solution to improve the strength of RF Waves? 
Relevant answer
Answer
Have wireless repeaters just like wired ones.
  • asked a question related to Computational Electromagnetics
Question
6 answers
Hi, I'm a new learner in the field of antenna design. I saw there are many ways to evaluate the surface current distribution on a patch antenna by using simulation software,  but would that be possible to do it in reverse?
Consider I have a known 2D current density distribution J(x,y) that can generate an EM field, and now I would like to reproduce this current on an antenna so that this antenna can generate the same EM field. Is there any book or software or methods that I can use to do it?  
As far as know, introducing slot on the antenna is one of the possible ways, but I didn't find any guidance on doing such design, so I'm looking for help here.
Thanks in advance!
Relevant answer
Answer
You can get a rough picture of your current distribution as the inverse Fourier transform of your desired radiation pattern.  Essentially, the far-field pattern of antenna is the Fourier transform of the near-field.  This comes from diffraction theory.  The near-field of the antenna is very close to the current distribution of the antenna.  Following this reasoning, it explains why narrow antennas produce broad patterns and why wide antennas produce narrow patterns.
There is clearly a bit of hand waving here, but this might be the simple answer you are looking for.
  • asked a question related to Computational Electromagnetics
Question
1 answer
Can any one help me find the equivalent circuit and how to calculate the resonnace frequency of a CSRR (not SRR) ?
Relevant answer
Answer
See Fig. attached.
  • asked a question related to Computational Electromagnetics
Question
3 answers
I have designed a vivaldi antenna. Now i want to compute its near field (not far field) directivity. Any one please help me.
Relevant answer
Answer
Sure!
  • asked a question related to Computational Electromagnetics
Question
2 answers
I'd like to know how I can simulate lamb wave in thin plate by using equations of lamb wave though physic of PDEs in COMSOL?And how I can get dispersion curve from COMSOL?
Relevant answer
  • asked a question related to Computational Electromagnetics
Question
2 answers
I am trying to simulate the temperature field for the gas metal arc welding in LS-Dyna. The computation goes well but in the post-processing the temperature shows zero.
I am enclosing my .k file. I will be very thankful. if anyone can help me out with this.
Regards
braj
Relevant answer
Answer
With GMAW i mean gas metal arc welding. In order to simulate the heat source i have used the Goldak heat source. The problem is that during post-processing the temperature distribution is zero. I have included my input file also. It will behelpful, if you can tell me where i m making mistake. I am very new to the world of LS-DYNA.
Regards
Braj
  • asked a question related to Computational Electromagnetics
Question
6 answers
What is the main difference between the boundary integral equations method, finite elements method and FDTD method- Antennas ?
Relevant answer
Answer
I am not completely sure what you mean by open and close space.  A technique like the method of moments is only required to mesh the objects being simulated.  It does not require space to be truncated or handled specially at the boundaries of your space.  Maybe this is what you mean by open space?  If so, method of moments and boundary element methods are very good.  I think, however, the best numerical method depends more on the device you are simulating and the physics you want to account for than it does anything else.
  • asked a question related to Computational Electromagnetics
Question
1 answer
i know that it provide an important courant, and loss of energy, but can i have more explanation about it