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Marcus Chang

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About Marcus Chang

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    Taiwan
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  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
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