# Dimon

Members

12

• Rank
Beginner

## Profile Information

• Country
Finland
• Are you University user?
Yes
1. ## Polarization properties

Dear All, Let us assume that we have a monostatic radar scheme when a Tx and Rx are collocated. A signal, transmitting by the Tx scatters on an electrically large object (human body) and returns to the RX. My question is what would be the best way to evaluate the cross-pol ratio (XPR[dB] = Total copol. signal[dBm] - total xpol. signal[dBm]) on the RX? Thank you! BR, Dimon
2. ## Solution of the electrically large problem by the RL-GO in FEKO 2019

Hello, I have found the following info in https://altairhyperworks.com/product/Feko/New-Features: "Diffraction effects for edges and wedges of perfect electric conductors (PEC) have been added to Feko’s RL-GO solver improving its accuracy". Ok, fine. Let us assume that I am modelling the multi-static RCS of a car, consisting of PEC body, and dielectric frontshield, interior and tires using RL-GO. Does it mean that the only metal body will produce the diffracted rays but the dielectric parts won't? Additionally, what kind of the diffraction model is used here? UTD? Thank you! BR, Dimon

Hello Professionals, How can I implement an ideal isotropic radiator in FEKO? I want to compare distribution of an electrical field without antenna gain using asymptotic methods. Can you help me with that? Best regards, Dimon
4. ## Simulation of EM field in highly dispersive (aerosol-like) dielectric media

Hello Peter, Thank you for your answer. The frequency range is 15 - 70GHz. So it is much higher than 10GHz.
5. ## Simulation of EM field in highly dispersive (aerosol-like) dielectric media

Hello, I have the task to evaluate magnitude, phase of E-field as well as angular and delay variance of it after transmission through highly-dispersive media (see image as attached). Particle size - 50um - 2mm and density of the particles is variable. Shape of the particles is sphere or cube. Materials are water, quartz, organics ets. Distance between Tx-Rx is 0.1 - 1m. Antennas are horns with HPBW = 10-20 degs. Freq is more than 10GHz. What would be the best computational methods for modeling of the task? What would be the best way to built geometry of the task? Thank you. BR, Dimon
6. ## 3D model - Hypermesh - FEKO

Dear Johan, Thank you for the information. As I understand there only are 2 ways to proceed: i) to design my own stp/igs (PTC, Solidworks) model from the scratch (preferable) ii) to find a specific CAD model with correct geometry. Am I right? BR, Dimon
7. ## 3D model - Hypermesh - FEKO

Hello Professionals, I want to make an electromagneic simulation number of cars. But, almost 1 month, I am trying to prepare my mesh model in Hypermesh for the purpose. I have tested a lot of 3D models, but problems such as small face, violation of a segmentation rule, faces have no common edge, overlapping/intersected faces etc appear again and again. I am not the high pro in car design and do not want to create my cars. Additionally, I need to consider physical property of materials in cars. That's why I am wiriting here and ask you to answer my questions please: 1. What kind of model do I need? Based on my month experience files such as *.STL, for instance, do not suit, however, PTC/SOliDWOrks native file, or STP/IGES work fine. Am I right? 2. Can Hypermesh remesh STL files: delete own grid and create a new one? Can I assign different materials for each face in Hypermesh? Where can I found tutorials on that? Note, I really want to learn how to prepare good mesh-grid for the FEKO from stl models, since the models are most populatr in internet. 3. Is there literature on Hypermesh? I wanna do my own meshgrid for the FEKO and validate it correctly. 4. What online resource with 3D cad models you may suggest for the followgin algorithm: 3D model -> Hypermesh-> FEKO. Thank you. BR, Dimon
8. ## ERROR 832: Segmentation rules have been violated

Hello JIF. Actually, before to write my question here, I have randomly googled the error. It was proposed to union the triangles without common edge. But it does not work well. However, HyperMesh may help indeed for my RL-GO RCS calcualtion. Thank you for you advice! You are the best! BR, Dimon
9. ## ERROR 832: Segmentation rules have been violated

Hello All, Currently I am working on calculation of vehicle RCS using asymptotic approach. I have tried many *.stl car models with low mesh density, but ERROR 832 did not give me to complete all my simulations. The issue was discussed many times in different forums, and some solutions were proposed. Unfortunately all these solutions do not help me. Thus I ask the question again here, and attached a certain model of car. Can you provide me some hints how to overpass the problem? BR, Dimon 1.STL
10. ## Mesh Density of Bulky Object at 72GHz

Hello JIF, Thank you for your help! It works! I got the idea of mesh grid optimization in FEKO. Well, actually you're right about complexity to select the right simulation methods for the model. But if I would point a goal criterion before calculation, then it might help. For example "highest accuracy", "fast computational time" or "balanced mode". Also, if you have a choice to select a trade-off between them in terms of number, then it might be useful as well. For example accuracy - 0.7, simulation time - 0.3. And of course the numerical criterion may also concern an optimization of mesh, wedges, edges etc... BR, Dimon
11. ## Mesh Density of Bulky Object at 72GHz

Thank you for your answer. Yes you' re right about asymptotic method, and it would be fine for me in terms of accuracy. But I thought that FEKO selects the model automatically depending on wavelength/object size ratio. If it doesn't then where can I manually select a certain asymptotic model? Could you advise where the setting is located in Feko interface?
12. ## Mesh Density of Bulky Object at 72GHz

Hello, I need to calculate RCS of large cube (8x2x1.5 m) at 70 GHz. Unfortunatelly, FEKO solver triangulates my object in too dense grid. Is there any way to reduce total simulation time? Are there any settings which I can play with to optimize my simulation? I used the most coarse settings of the meshgrid in my simulation. But it still works to loooooong.... BR, Dimon
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