Question
Asked 28th Jun, 2019

I want to simulated resistive sheet based EM wave absorber using CST ? what approach should i follow ?

EM wave absorber

Most recent answer

In the following
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Popular answers (1)

Mondeep Saikia
Queen's University Belfast
hi,
i guess the question is about how to define a resistive sheet of surface resistance R ohm/sq.
In HFSS an impedance boundary can be used.
In cst you have to define a new material. select type as ohmic sheet.
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All Answers (7)

Krunal Patel
Narsee Monjee Institute of Management Studies
You should follow time domain approach. With plane wave excitation measure the scattering characteristics of the incident wave. If you are using waveguide ports then measure the transmission and reflection coefficients.
Siamak Sarjoghian
Queen Mary, University of London
You can set the electric and magnetic monitoring in the frequency of interest and check the field propagation as well.
Ardhendu Kundu
Institute of Engineering & Management
In addition to what has been mentioned by Krunal Patel , you can use some electric field/magnetic field probes on the other side of the absorber and measure the field intensity in presence and absence of absorber.
Thank you.
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Mondeep Saikia
Queen's University Belfast
hi,
i guess the question is about how to define a resistive sheet of surface resistance R ohm/sq.
In HFSS an impedance boundary can be used.
In cst you have to define a new material. select type as ohmic sheet.
5 Recommendations
Siamak Sarjoghian
Queen Mary, University of London
hi,
for this you have to check the dielectric properties of the sheet and then make new material using this properties, then you can use and simulate it.
Awanish Kumar
Indian Institute of Technology Mandi
Yes sir I used the same steps and tried to reproduced a result which has already published but i did not get the results. @ Mondeep
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Similar questions and discussions

Can anyone help me with this CST simulation?
Question
5 answers
  • Hugo PienaarHugo Pienaar
I'm trying to design a tunable microstrip combline filter with its initial f0 at 2.45GHz, with my resonator's electrical length at 45 degrees to provide maximum tuning range. I'm having problems with my CST simulation, where I'm trying to find the unloaded Q-factor of a resonator. I don't trust the results I'm getting (a Q0 of over 1000 for a 18um copper trace on a Rogers substrate, which I thought would be below 300) and am wondering if I'm using CST correctly.
The only thing I think can be wrong with the dimensions is that I might have chosen a PCB with too thin or thick a dielectric thickness. What are some common thicknesses used for applications at 2.45GHz?
The below list is the steps that I've followed. Hopefully something erroneous pops up to someone more experienced than I.
I've set up the simulation for Q0 extraction as follows:
  1. I entered the required parameters: resonator's height, width, length; substrate's height, width, length (based on the resonator's dimensions), and eps_r; the vias' outer diameter and offset from the bottom.
  2. I created the substrate, groundplane, and resonator, defined their geometries, materials, and positions, and placed them accordingly. I then created an airbox and set its position on top of the substrate with appropriate dimensions, and set its material to vacuum.
  3. I then boolean inserted the vias into the substrate, groundplane, and resonator. After this, the resonator and vias were boolean inserted into the airbox. I wonder if the boolean operations I performed were incorrect, as I'm not sure what exact operations to follow in order to ensure proper electrical connections.
  4. I selected the eigenmode solver, used the tetrahedral meshing technique, and defined the frequency ranges.
  5. The simulation was then run: two modes were found, both not at my desired f0 but almost double and 4x respectively, both showing an unloaded q factor of way higher than 300 (which I thought was a practical max for copper on most Rogers substrates).
My goal is to get Q0 at my desired resonant frequency, but the mode frequencies CST gave me is not at 2.4GHz. I don't think it's a fault with the dimensions, but I could very well be wrong. I suspect I might have made a mistake in how I set up my simulation.
Please advise me on any possible errors I could be making, or perhaps better ways of going about the simulation.
I can't seem to find anything on YouTube detailing the process I'm embarking on, nor do the papers I've found detail exactly how they arrived at their filter's dimensions from simulation, they simply provide their resulting parameters.
Thank you for your time.

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