I am trying to design a Spiral antenna in CST. When I use macros and then coils and then spiral antenna. This geometry has only one arm. How can I construct a 2 arm spiral antenna?
...Dont forget that a discrete port should be attached it (discrete face port even better since it reduces the intrinsic port inductance). And in case of a real world prototype, a balun should be implemented, since both arms are supposed to be fed by a balanced transmission line.
Thankyou. I am having trouble generating the second coil. After generated first coil, I tried to enter new parameters with the coil starting point at 180. But I cannot see the second coil. Should I select something so that there will be second coil??
Kohli
What Malcom said was to select the first coil, right click on it an using the "transform" option apply a rotation to it, keeping the "copy" option on so that the original arm is not lost. You can click on preview to see what the result is when rotating it.
Thankyou Marcelo. Able to generate second coil now. Just now playing how to change the parameters, it looks like right now. Could are overlapped
I am running simulation on CST for 2 arm archimedian spiral antenna for 2 days. My machine is a strong machine with 180 GB memory with 12 cores. How long does it take to complete the simulation on CST? Please guide
How many mesh cells are there? Are you able to use symmetry? Unfortunately there isn't a way to use the kind of circular symmetry your problem exhibits to save computation time (as far as I know), but you may be able to put a magnetic conductor through the mid-plane of the metal spiral to at least halve computation time.
Thankyou malcolm,
I was able to run and complete the simulation. Now I am facing 2 problems:
1. If I want to change the parameter like the winding progress. my design is all over the place. like it is overlapping on each other and I am not able to fix it. There should be an easy way to change the parameters and not go manually to rotate the design to fix manually.
2. How can I see the result of Impedance like Z parameter and directivity.
Thankyou in Advance.
Meenakshi
Hi Meenakshi
Your PC seems alright to this simulation. If youre using the transient solver, starts the simulation from 0 (DC) even though your band is far from it - it helps shorten the simulation time - rule that applies only for TEM modes as yours.
The geometry youre using is complicated, you should investigate which step from the history list is creating havoc when one parameter is changed. Usually the history list has the steps marked in red where some problem happens, its a good starting point to investigate.
The Z parameters can be computed using the template post processing (SHIFT+P shortcut) or directly on the ribbon that contains the S-parameter, one of the icons is related to the Z parameters.The directivity is seen on the farfield monitor you set before the simulation started. If you didnt ask for it prior to the simulation you wont see it.
Just for curiosity, try to run your simulation also with the Frequency domain solver (F), it might result in shorter simulation time due to the weird geometry of the antenna. Tet mesh represents more accurately these curved and complex geometries sometimes.
Thankyou so much Marcelo,
One more concern, I am also trying with the rectangular cross section for my spiral in CST. But at the center everytime both the turns are joining each other. Can I separate them? I tried a lot. Pease look at my design attached and guide please.
If the two spirals meet in the middle then create a cylinder or block or what ever shape you want and insert it into the spirals where you want the gap, then delete it, leaving a gap.
Hi Meenakshi
A geometrical model of a spiral antenna (Spiral Antenna.cst) is attached. I hope to help you.
The same procedure you did to make an arm is the same thing you have to do to make the second one. The difference is that they are rotated 180 degrees. For example, when you define the values of the first arm, you say that your spiral begins at 90 and ends at 180, then the second arm begins at 270 and ends at 180.
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