Type: Posts; User: maxwellian

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  1. Closed: Re: Measuring propagation loss between two dipoles over free space

    If the antennas are away from the near-field zone of one another (~15 cm at 1 GHz, less at higher freqs), why don't you just use the Gain pattern for the dipole, find the gain at each freq associated...
  2. Closed: Re: Why do I get back radiation when simulating this horn antenna??

    Have you studied the currents on the outside surface of your horn antenna, particularly around the mouth of the horn? It sounds like you might have high currents that are leaking back onto the outer...
  3. Closed: Re: size of waveport for antipodal vivaldi antenna feed

    It might be a good idea for you to do a convergence test on this for yourself. Start by making the waveport something like 2X the gap on each side and above/below the conductors, and simulate the...
  4. Closed: Re: Archimedean Spiral antenna....unbalanced....Vswr problem

    What do you mean by unbalanced? Are you using an unbalanced feed, or is there some aspect of the design that causes this to be a non-complementary antenna design? Can you post a picture of the...
  5. Closed: Re: Simulating Self inductance value of a microstrip trace

    You can't have inductance without at least some implied return current path. However, there are software tools that will build in the ground plane assumption for you. There are a number of free...
  6. Closed: Re: Archimedean Spiral antenna....unbalanced....Vswr problem

    What impedance did you use for your lumped port? A complementary Archimedean Spiral should exhibit an input impedance of 188 ohms.
  7. Closed: Re: [HFSS Help!] Gain obtained for monopole is higher than theoretical value?

    How much space are you modeling between the monopole and the absorbing boundaries? I'm not sure about the rules of thumb for HFSS, but sometimes with 3D field solvers you need to have enough space...
  8. Closed: Re: HFSS mesh problem: simulating a big structure (4m) with a tiny component (1mm).

    Delcross has a Shooting and Bouncing Rays (SBR) code called Savant that can do this for high frequencies where the problem size is very large. They can import 3D full-wave EM models for isolated...
  9. Closed: Re: How to connect the port to the spiral in Sonnet ?

    Just a reminder: Unless you change the boundary conditions of your simulation space Top or Bottom cover, the entire outside of this box will be treated by Sonnet as a PEC boundary. It's convenient...
  10. Closed: Re: Nice website for modelling structures in Ansoft HFSS, CST, Feko, IE3D etc..

    This web site is a bit dated. For instance, Flomerics MicroStripes is actually now a component of CST Microwave Studio. There are other technical issues on this web site that make it appear to be...
  11. Replies

    Closed: Re: The Width of the lumpport in HFSS

    I would recommend you use the pin width. That way your model will contain the correct current profile as it approaches the device pin. Otherwise, you will lose the proper modeling of the extra...
  12. Closed: Re: MentorGraphics acquires certain asset of Zeland-Any Comm

    It would be interesting to hear from Dr. Zheng on this.

    I have heard that it becomes the new Mentor HyperLynx3D tool. But Mentor doesn't play in the high frequency RF simulation area very much. ...
  13. Closed: Re: Simulation of a multilayer interdigitated capacitor

    Yes, this can be an issue. If you use thick metal definitions in Momentum, you have to realize that Momentum will effectively increase the thicknesses of your dielectrics in order to create models...
  14. Replies

    Closed: Re: momentum artwork and primitive?

    That is interesting. There should be no difference when you simulate the design in Momentum, because the artwork should be exactly the same. Have you looked at the Momentum mesh? Can you post the...
  15. Replies

    Closed: cost ie3d


    I'm not sure what you are referring to when you say "mesh the vertical planes," but I do know that Momentum, Sonnet and IE3D all have ways of modeling true metal thickness so that...
  16. Replies

    Closed: how much will it cost to buy ie3d

    Good point. But you would realistically use these 3D MoM tools for scattering problems and full 3D structures (like radar cross-section analysis of a full airframe) that are electrically too large...
  17. Replies

    Closed: hybrid ring + rat race circuit

    Why are you using a full 3D EM solver to model a planar circuit? Planar EM simulators can model structures like this so much more quickly and easily, and drawing the circuits is far easier and...
  18. Replies

    Closed: what is ie3d


    IE3D is not a full 3D EM simulator. Full 3D EM simulators mesh volume, and IE3D only meshes surfaces. They claim to be able to do 3D bodies, but they are limited to rather simple...
  19. Closed: what is finite ground and infinite ground plane


    Is that true for the planar solver in Ansoft Designer?

    In many cases, you can consider a finite ground plane to be infinite for large antenna systems. However, I think a thorough antenna...
  20. Closed: plane simulators


    The infinite ground plane assumption is implicit in the planar EM simulators that operate in an "open" simulation environment. The MoM solution that they use is based on the assumption of...
  21. Replies

    Closed: Re: Any company taking the AXIEM-Challenge?

    Usually an "in-house" EM software tool is chosen because it provide reliable results, is accurate and is fast. It's not only about speed, or we would just use circuit theory tools all the time.

  22. Closed: Re: In HFSS, why ports need to far away from discontinuity?

    Yes, you also have to be careful not to use lumped ports if they could possibly couple to other things near them. Since they are not de-embedded, you should be careful about using them at high...
  23. Closed: Re: In HFSS, why ports need to far away from discontinuity?


    I think it is so that the stray fields from your discontinuity are not picked up in the field port. This would cause numerical error in the S-parameter extraction.

  24. Closed: Re: PIFA design

    I think it's better to use "Open--Add Space". That way, it's less likely that you might have absorbing boundaries too close to your model, where they might absorb the field lines in a non-physical...
  25. Closed: Re: PIFA design

    Use a lower value for energy criteria for simulation conclusion. Sounds like you have energy that is still trapped in your model that has not yet dissipated or radiated. Are you sure you are using...
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