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What is dispersion?
See the links below for info on numerical dispersion in FDTD:
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http://faraday.ee.auth.gr/papers/Zygiridis2004b.pdf
obviously the faster the processor, the faster the EM solver will be for problems that are not RAM-constrained. The advantage of adding more RAM is that it avoids swapping to hard disk (virtual memory) which is much slower. HFSS can access up to 3 GB of RAM on XP, and I would put as much as you...
plasma has a good point about scanning phased arrays. Predicting the active element pattern and active impedance can take a prohibitive amount of time with an EM solver. It is the active response you need since it includes mutual coupling between the array elements.
Yyes I agree with adel. One of the most difficult problems that I deal with in EM analysis is how to address large finite arrays (finite frequency selective surfaces are in the same class of problem).
Typically, small arrays can be analyzed using a full-wave solution (FEM, MoM, etc.) and then...
See the attached file for an overview of antenna measurements, with some details on the different methods for measurement radiation patterns.
Also, these two links have some info as well:
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Good luck.
In HFSS, one solid (3D) object cannot intersect another or it will produce a Boolean error. You should subtract one object from the other. So in your case, you can subtract the coax pin from the substrate that is below the upper p_atch. That should fix the error.
Seeding the mesh means adding...
Here are a couple of ideas:
1. Move the radiation boundary further away from the transmission line so that it is not interfering with any reactive fields. You don't want it leaching off the fields.
2. Move the PEC boundary further away so that it isn't interfering with the reactive fields. You...
The concept of "lumped ports" is a basic one and can be implemented in various methods (MoM, FEM, TLM, etc.). For example, NEC uses a voltage lumped gap source. In HFSS, you draw a lumped gap source using a 2D rectangle and assigning it as a port. Set the impedance and calibration line. A small...
Yes a lumped port can be used for this type of excitation. It will give the antenna input impedance across the feed gap.
A more rigorous model could include the type of feed (possibly with balun) that will be implemented. A slot spiral can be fed using a planar infinite balun. Metal spirals...
If you are referring to a stripline, where the signal line is embedded inside two dielectrics, then yes a waveport can be used for this.
If you are referring to a transmission line that begins inside a substrate and inside a model, then you can use a lumped port for this. However, I have seen a...
Convergence Problem???
I would recommend using more than 3 adaptive passes as a default. For HFSS, I usually set deltaS to 0.005 and maximum number of passes to 10 or 12. Check the convergence before viewing the results. It is a good habit to get into.
Also remember that converging on input...
I would use only lumped ports when using wave ports are not possible. Wave ports use a 2D solver on the port cross-section to obtain the modes that will propagate down a transmission line of infinite extent. They can be used for many geometries such as waveguides, stripline, CPW, microstrip...
This is a common problem in HFSS. As the first post said, seeding the mesh down to 1/10*lambda will make sure the boundary is sufficient. Make sure the conductor has the finite conductivity (no PECs) and include the loss tangents of any substrates.
Also, the radiation boundary doesn't need to...
hfss stripline waveport
The port setup for stripline should extend to the top and bottom grounds, and should be wide enough so that the fields from the trace do not attach to the sidewalls of the port.
For HFSS models, the recommended port width is 8*w if w>h and 5*w if w<h. Make sure that the...
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