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# Computational Electromagnetics - Science topic

Explore the latest questions and answers in Computational Electromagnetics, and find Computational Electromagnetics experts.

Questions related to Computational Electromagnetics

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.

list of SCI journals that will take low time for responding

( related to MIMO antenna and computational Electromagnetic)

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

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 !

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.

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?

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.

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.

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:

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?

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.

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?

- 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?

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?

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..

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!

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?

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?

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.Actually, I'm expecting answer to perform a computational program and its code related concept.

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

Does anyone know if the poisson solver will enable the calculation of capacitance between electrodes with a cylindrical structure?

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?

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*FWhy did Feynman fail? Can you find an example to support Einstein’s claim?

Attached file presents and reviews Feynman’s analysis and calculation.

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

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.

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.

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!

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.

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

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?

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.

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.

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?

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

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..

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?

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 ?

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

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!

how can we use cst code for cyclotron magnet simulation? is it a realible code for this purpose?

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?

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!

Which software is best for finite element method analysis (FEM) to detect the magnetic field using photonic crystal fiber?

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!

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.

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.

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.

Can any one suggest application of microwave absorbers in 5G communication systems?

Why the E plane beam width of monopole antenna gets narrow when we increase the width of ground plane of monopole antenna???

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

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.

I want to plot the sections c AND d of Fig 3 of attached paper in CST software. would you help me?

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.

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.

Now a days ,For multiple frequency for different application,we must require frequency reconfigurable antenna.But it is challenging to design .

how to obtain Rcs dBm vs theta in polarization reconfigurable antenna

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?

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.

How can I simulate the graphene in CST?

how can i define it?

please send me a tutorial or help me.

thanks

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.

build a single slot waveguide antenna, to optimize parameters, length, shift . How to optimize. something wrong

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

As i haven't use Quarter-wave transformer before i am confused. Your response guys would help me alot.

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?

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!

Can any one help me find the equivalent circuit and how to calculate the resonnace frequency of a CSRR (not SRR) ?

I have designed a vivaldi antenna. Now i want to compute its near field (not far field) directivity. Any one please help me.

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?

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

What is the main difference between the boundary integral equations method, finite elements method and FDTD method- Antennas ?

i know that it provide an important courant, and loss of energy, but can i have more explanation about it