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Marcus Chang

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Everything posted by Marcus Chang

  1. Dear Mel, Related to your suggestion 2, do you mean we can simplify the structure of the absorber to be a cubic as shown in attached .cfx file? We finally get the results of the S21 and compare these two simulations w/ and w/o modification, we found that if we did the simplification, the S21 (-65dB) is 20 dB higher than original one (-85dB). BR/Marcus Absorber_Cuboid_15.cfx before_simplification.cfx
  2. Dear Mel, Please see below screenshot link, only antenna pair rotate. https://drive.google.com/file/d/1CAzEFV7QyJi0L9x0kIxtEUOVJSroXHiy/view?usp=sharing Sweep = 2 degrees BR/Marcus Sphere CATR S21.out
  3. Hi Mel, Even 1 hour, it is still too long, because in order to get a polar plot-like with 360 degrees S21 patterns, we need to rotate horn antenna pair per 2 degrees and run 181 times. So we need to spent 181*1.1 hours to get the results, even more, for the another confidential file, (181*3 hours=22 days). In real measurement, we will let 2nd port on. Is there any other solution to save simulation time? Such as modify the mesh or some simulation setting we neglect, etc. BR/Marcus
  4. Dear Mel, Please see attached .out file run in our sever with 256 RAM. Even though we spent 1 hrs to solve it faster than our expectation. Actually, another simulation case (confidential) we run, we spent 7 hrs to solve it. The difference between these two simulations are the location of the horn antenna pair, sphere and the strcture of the reflector (smaller structure compared to the file I give you). I also attached this .out file, please check. Thanks a lot. BR/Marcus Sphere CATR S21.out Hallow Sphere CATR S21_MoM_new.out
  5. Dear Mel, Thanks for reply. To clarify the problems we face, please see attached .cfx (similar to our case), in such simulation, we spent several hours to simulate it. Is there any suggestions? Could you please help us modify the setting if you have any better idea? Thanks a lot! BR/Marcus Sphere_CATR_S21.cfx
  6. Dear FEKO support team, Due to the paper submission deadline is coming soon, my I have your response within this week? I’m sorry if this has caused you any inconvenience. BR/Marcus
  7. Dear all, So far I have two questions shown as below, please check: 1. Is it possible to reduce the simulation time by modifying the setting, the .cfx file is shown as attached. Next step we will add a reflector with a size slightly larger than the sphere, and for this reflector, we need to take diffraction issue into account. For this kind of problem, if we add the reflector described as above, do you have any better suggestions for us to keep well accuracy and also spend less time to simulate it? In this scenario, we need to rotate both TX/RX horn per two degrees in a circle (simulate 181 times by using parameter sweep in FEKO) and reflector included, we spend 5 hours for each simulation, therefore, we will spend 181*5 hours, 37 days to solve it by using workstation with 56 processors CPU (Intel(R) Xeon(R) W-3175X CPU @ 3.10GHz) and 512G RAM. The total simulation time and more details for one of simulations are shown as below from the end of .out file: In this case, the solver for reflector we use is PO, however, as mentioned above, we need to take diffraction issue into account, but if we use MoM/MLFMM method, the simulation time will be much more longer than using PO method. For this scenario, please provide us any suggestions to avoid this issue. 2. There is a weird results in S-parameter for attached .cfx file, that I have no idea is, there is a little difference between S21 (-85dB) and S12 (-90dB) in such symmetrical geometry model. And also, these two S-parameter values are lower than it simulated with two horns only (S21&S12=-79 dB), it doesn't make sense, the S21 values for TX/RX only should be the lowest when compared with the other scenario if we add additional objects. Even though the value for this difference is relative small, kindly give us explanation for this deviation, such as, it is caused by asymmetrical meshing or any mistake in my simulation setup, etc. P.S: Due to the reflector we design is confidential, attached .cxf file we provide is not including reflector. SUMMARY OF REQUIRED TIMES IN SECONDS CPU-time runtime Reading and constructing the geometry 2.326 2.326 Checking the geometry 1.581 1.580 Initialisation of the Green's function 0.000 0.000 Calcul. of coupling for PO/Fock 12030.895 12030.895 Transformation to equivalent sources 0.000 0.000 Ray launching/tracing phase of RL-GO 0.000 0.000 Calcul. of the MLFMM transfer function 0.483 0.484 Fourier transform of MLFMM basis funct. 2.414 2.413 Calcul. of matrix elements 139.400 139.399 Calcul. of right-hand side vector 8747.818 8747.818 Preconditioning system of linear eqns. 18.643 18.643 Solution of the system of linear eqns. 423.926 423.927 Eigensolution for characteristic modes 0.000 0.000 Determination of surface currents 0.000 0.000 Calcul. of impedances/powers/losses 0.020 0.021 Calcul. of averaged SAR values 0.000 0.000 Calcul. of power receiving antenna 0.000 0.000 Calcul. of cable coupling 0.000 0.000 Calcul. of error estimates 0.000 0.000 Calcul. of electric near field 0.000 0.000 Calcul. of magnetic near field 0.000 0.000 Calcul. of far field 0.000 0.000 other 1.593 1.594 ------------ ------------ total times: 21369.099 21369.100 (total times in hours: 5.936 5.936) Specified CPU-times are referring to the master process only Sum of the CPU-times of all processes: 598334.848 seconds ( 166.204 hours) On average per process: 21369.102 seconds ( 5.936 hours) Peak memory usage during the whole solution: 930.652 MByte (refers to the master process only) Sum of the peak memory of all processes: 21.454 GByte On average per process: 784.597 MByte BR/Marcus 20191017.cfx only two horn.cfx
  8. Dear all, So far I try to modify solver setting, active “Solve model with the multilevel fast multi pole method (MFLMM)”, and it’s seemed much more faster now. If there is any further question, I will let you know, thanks a lot. BR/Marcus
  9. Dear support team, Recently, we run a simulation for a absorber placed between sphere two horn, we would like to get S parameter from this setup. However, this simulation was stuck as shown in attached figure, LU decomposition of the matrix, for almost two days. And also I think our server system is good enough for this simulation with 512 RAM. In this simulation, how can I decrease the simulation in hour through the setting, I think it is must be something wrong in my setting for absorber in this simulation. Because it is one of an urgent studies for a paper, pleas help us solve this issue ASAP, appreciated. BR/Marcus
  10. Hi Mel, Is this warning message affect the results of the power received by near field receiving antenna? BR/Marcus
  11. Hi Mel, After I upgrade Feko to version 2019, and try to solve the same problem, another similar warning show up again as below, please check: The following message from the master process (MYID= 0): WARNING 53119: Possibly inaccurate active power (far field gain) when using equivalent sources in a coupled environment is there any suggested solution to solve it? BR/Marcus
  12. Dear all, Recently, I try to use a near field data as the source, and try to get it's far field results. However, it shows a warning message as below: WARNING 3411: No accurate power calculation possible if two non-orthogonal elementary dipoles of the same type are at the same position Received message from server process 2: WARNING 2407: Computation of the near field of a Hertzian dipole not possible at the dipole location Could you help us check what does it exactly mean in this case? Is there any solution to solve it? BR/Marcus validate NFsource radiate direction.cfx campactrange_PlaneWavesource_cornerreflector_190827_Ray_01_NearField.efe campactrange_PlaneWavesource_cornerreflector_190827_Ray_01_NearField.hfe campactrange_PlaneWavesource_metallicsphere_190827_NearField.efe campactrange_PlaneWavesource_metallicsphere_190827_NearField.hfe
  13. Hi @Torben Voigt, Recently, I tried to simulate a near field source radiate a signal to CATR reflector and use near field receiving antenna to receive the power of scattered field. The schematic diagram is shown as attached, please check it. And I found that the size of the reflector is 0.37m*0.37m, around 12 times lambda (operating frequency = 10 GHz)...if I would like to use GO method for it, it is smaller than 20 times lambda you suggest. Due to I spent almost 2 days to solve this kind of problem by using MoM/MLFMM method, is it possible to use GO method in this case? What is the tolerance range for this problem if I use GO method not MoM method? Or is there any other suggestion, such as modify the setting, to boost the simulation? BR/Marcus
  14. Hi @Torben Voigt, Now I have a question that, is it possible to change the size of corner reflector (s=3*c0/(fmin+f_inc*i), i=0 to 2) for each simualtion (per frequency, such as 9GHz, 10GHz and 11GHz in this case), if it can, can you help me modify this .lua file? BR/Marcus MacroRecording_multifreq91011GHz.lua antenna_only_NF.hfe antenna_only_NF.efe
  15. Hi @Torben Voigt, I've tried to use this .lua file to run the simulation, however, it still doesn't work, and the error message is shown as below, please check: ERROR 30968 in line 40 of the file test2.pre: Error in opening the file 02_NF source_PEC corner reflector_190406_sphere placed 72 lambda_alt_NearField_1 To my understanding, the input characters should be like this: 02_NF source_PEC corner reflector_190406_sphere placed 72 lambda_alt_NearField_1.efe not like this: 02_NF source_PEC corner reflector_190406_sphere placed 72 lambda_alt_NearField_1 So I would like to check with you, how can I write a propreiate code to generate the character string shown as above, such as: 02_NF source_PEC corner reflector_190406_sphere placed 72 lambda_alt_NearField_1.efe 02_NF source_PEC corner reflector_190406_sphere placed 72 lambda_alt_NearField_2.efe 02_NF source_PEC corner reflector_190406_sphere placed 72 lambda_alt_NearField_3.efe BR/Marcus test2.cfx temp.lua
  16. Hi @Torben Voigt, Here is another question for scripting related to this case. If I have three E-field and H-field data, and I would like to use it as my source in next simulation. So I write a script as attached, however, it seemed like I must to input file named including .efe or .hfe these characters. I want to let the input looked like this: but I don't know how to modify this script, such as how to add additional .efe or .hfe these characters to the code as below: properties.EFieldFilename = [[02_NF source_PEC corner reflector_190406_sphere placed 72 lambda_alt_NearField_]]..i properties.HFieldFilename = [[02_NF source_PEC corner reflector_190406_sphere placed 72 lambda_alt_NearField_]]..i If I use the script as shown as above, it will be looked like: BR/Marcus 02_NF source_PEC corner reflector_190406_sphere placed 72 lambda_alt_NearField_1.efe 02_NF source_PEC corner reflector_190406_sphere placed 72 lambda_alt_NearField_1.hfe 02_NF source_PEC corner reflector_190406_sphere placed 72 lambda_alt_NearField_2.efe 02_NF source_PEC corner reflector_190406_sphere placed 72 lambda_alt_NearField_2.hfe 02_NF source_PEC corner reflector_190406_sphere placed 72 lambda_alt_NearField_3.efe 02_NF source_PEC corner reflector_190406_sphere placed 72 lambda_alt_NearField_3.hfe temp.lua
  17. Hi @Torben Voigt, Due the the version problem, could you please help us provide the modified file in previous version (2018.2-338937 (x64)) in this transition period? BR/Marcus
  18. Hi @Torben Voigt, If I would like to do multi-frequencies simulation, such as with a bandwidth, how to use script to import near field data for every single frequency in this case. Because when I try to run a multi-frequencies problem, I use the first .cfx file and add multi-frequencies setup, I can get a NF data with multi-frequencies. But when I use this NF data as my equivalent source (NF source), the error message was shown as below: ERROR 3392: The near field source cannot be used inside an implicit frequency loop (frequency dependent data) And I check there was a member had similar problem, it seemed like I need to solve it with EDITFEKO. Can you provide us an example (EDITFEKO), for this three files, such as how to write a loop then I can finally get a plot with RCS values in a bandwidth, such as 9-11 GHz. BR/Marcus
  19. Dear Mel, Is there any update for the modified .cfx file? Looking forward receiving your response. BR/Marcus
  20. Dear Mel, Thanks for your help, it works now! BR/Marcus
  21. Dear Mel, I have tried to union all the parts, and it still didn't work. And also, due to there is an error if I use waveguide port, so I use lump port alike, to excite it. It would be grateful if you can help us modify the settings for this simulation. BR/Marcus
  22. Dear support team, Recently I try to simulate a very simple patch antenna working at 2.45 GHz, but it show an error message as below, please check it: ERROR 3849: Wrong specification of the medium for a metallic triangle and I try to open POSTFEKO and use "Find Element" method, to see the problems occurs by which triangle, but two meshes seemed like not overlap. can you help us check what's going on in my simulation? Thanks a lot! BR/Marcus patch.cfx
  23. Dear Support Team, Recently we had an easy exercise of RCS simulation in FEKO with large element object. Due to the size of the file is exceed 48.83MB, so please check below link: https://drive.google.com/file/d/1oee6-vL0pyZJTeJ-w8NQA7ZYRi1ycWM6/view?usp=sharing There is two problems that: First, if you use this file to run simulation, "the triangular mesh overlap..." error message will show up in the end. Then I try to union these separated dielectric objects to an object and exported to a new .stp file then import it again to replace original object. The first problem is solved, but there is a second problem occurs, out of memory by using our workstation with 256 GB RAM. And also I have try the other method, such as replacing the free space region between two objects in the file by using a dielectric constant equal to 1 with FEM solver, and modify the mesh quality to FAST, refinement factor to coarse ,minimum element size to medium in "Create mesh", but it seemed not better than before. Please help us check what's happening to our simulation file, and provide us some guidelines if we face this kind of problem next time. Thanks a lot. BR/Marcus
  24. Hi @Torben Voigt, It works now, the received power for RX antenna in situation of corner reflector is also 10 times larger than metallic sphere. Thanks for your suggestion! BR/Marcus
  25. Dear @Torben Voigt @mel @JIF, Recently, I try to run some simulations for metallic sphere and corner reflector respectively, the results for these simulation is weird, the received power bounced by metallic sphere is larger than corner reflector. But actually, the RCS for metallic sphere should almost 10 times smaller than corner reflector, no matter it's calculated by formula or simulated in FEKO (I also upload these simulations as attached, please check) So I would like to check with you again, to see what's happened to the setting in FEKO. BR/Marcus 190406.7z
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