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Everything posted by FEKOFan

  1. Ok. Looking forward to reading the outcome of discussions. For other problems I want to solve I would also have to calculate common mode currents on the exterior of the coaxial cable braid when connected to an antenna. I am not sure if this will be possible.
  2. Thanks, understood. That works fine now, after adding also a PEC to the model. So I can calculate a source connected to a dummy load by a piece of RG58. Now I want to replace the dummy load with a dipole. I have a connector with two pins at the end of the coax. The position of the connector is defined because I checked "Cable path terminal" and is set to CablePath1.End. How do I connect a wire (half of the dipole) to Pin1? Even if set the Connector position to 3D Coordinate I can't see how to distinguish the position of Pin1 and Pin2.
  3. I have been trying to do this using a transmission line. I put a wire port on a wire and then add a transmission line to the model, but the TX Line object doesn't give me enough flexibility to define all the interconnections of a halfwave balun. Once a figure out how to do this I would like to model more complex baluns and I can't see how I will be able to do that. So I looked at the Cable models. These allow me to define Pin1 and Pin2 at the end of a coaxial line. Started with the simple example below, a complex impedance at the end of the coax and a source at the start. However this model throws an error when I do CEM Validation saying that the Cable Harness does not have an excitation defined. It seems that FEKO does not recognise this source in the same way that it does for Sources attached to a Wire Port. But I cannot attach a Wire Port, because there are no wires in this model. Even if I add a wire, I can't find how to connect the ends of the wires to the Pins of the connectors. More suggestions would be much appreciated. Best regards, Ed
  4. Thanks. Not sure yet, but it gives me a place to start, I'll have a look to see where it takes me. Best regards, Ed
  5. I would like to model a coaxial halfwave balun, a dipole and a coaxial line in the typical 4:1 configuration of the halfwave balun. Can I have some guidance on how to do this please? I have modelled dipoles and Yagis with FEKO, but not sure where to start to model the coaxial line and the halfwave balun. Then I would like to be able to calculate some balun parameters such as balance ratio, bandwidth, impedance transformation, etc. Thanks, Ed
  6. Thank you very much for your replies, they are very helpful. The attached files should make clear what I meant. The model files are as follows: 1. Yagi_Pattern_Optimisation-0.cfx is the same as the original example delivered with the software, but I converted the active element into a Polyline. This makes no difference to the results of the calculation. 2. In Yagi_Pattern_Optimisation.cfx, I inserted two corners into the Polyline that defines the active element. No change to the physical problem, but the Impedance magnitude is different to the previous case when using a Standard Mesh. I need these corners because my plan is to bend the active element, but first I want to double check that I don't get changes in results because of numerical issues. 3. In Yagi_Pattern_Optimisation-1.cfx I added local mesh size of lambda/20 to the three wires that form the active element polyline. Different results again as shown in the ImpMag.tif file. If I use a Fine Mesh for the whole structure, the Impedance Magnitude of models in 1. and 2. is the same, but how can I be confident that convergence has been achieved? I tried Create Mesh > Mesh Size : Custom to define a mesh smaller than Fine, but meshing time seemed to take forever. Further advice would be much appreciated. Yagi_Pattern_Optimisation-1.cfx Yagi_Pattern_Optimisation.cfx Yagi_Pattern_Optimisation-0.cfx ImpMag.tif
  7. I would be grateful if you can explain in more detail how to use Polyline Refinement expanding what is already in the UserManual.pdf. Consider the Yagi_Pattern_Optimisation.cfx example from the ExampleGuide. Let's say that I want to know how the Yagi performs when the elements have different shapes (bent, folded dipole, etc). To start, I replace the straight Active Element with a Polyline. After recalculating, all results are the same as before as one would expect. Now insert two corners in the Active Element, for example, at N: L1*lambda/2 and N: -L1*lambda/2, so the Active Element has 3 sections with the Port in the middle. This doesn't change the physical problem, but recalculation shows a significant difference in the impedance magnitude compared to the original model using a standard mesh. Ideally I would like to refine only the mesh of the Active Element. If I use Polyline Refinement do I have to copy the same Corners that I defined for the Active Element? What values should I set for the Radius and Mesh Size in this context? How can I guess what is a reasonable Mesh Size? Many thanks in advance.
  8. After reading the Getting Started and User Manual there are a number of Antenna Far Field parameters that I cannot find how to calculate: - Front/Back and/or Front/Rear as a function of frequency - Beamwidth to -3dB levels - Main Lobe/Side Lobe ratio - Antenna Temperature (T) and G/T as a function of frequency I could get some of these manually from a Far Field diagram, but a numerical output from the program would be more practical. Would be most grateful if someone can help.
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