I am designing a patch antenna with coax feed for 3GHz frequency. While assigning radiation box the height of the box needed to be assigned I found it should be above lambda/4 which was around 25mm for 3GHZ. I increased the height and saw what happened. I found that while doing the following steps
1. When the height of the radiation box was at 32mm and solution frequency which I gave during analysis setup was 3GHz, S11 resonance occurs at 2.71GHz. The gain and directivity plots were calculated.
2. I changed the solution frequency to 2.71GHz and now the resonance occurs at 2.95GHz. The gain and directivity plots were not calculated, a cross mark came near that
3. Now again I changed the solution frequency to 3GHz and now the resonance occurs at 3GHz. The gain and directivity plots were not calculated.
The doubts are:
1. When I am doing step 1 I should get the same results as step 3 but why I am getting different results I am using same parameters but my answers are different
2. Why after doing these three steps only I am reaching what I expect.
See this if it helps:
https://courses.ansys.com/index.php/courses/ansys-hfss-getting-started/lessons/solution-setup-using-ansys-hfss-lesson-3/#:~:text=Solution%20frequency%20is%20used%20to,one%20lecture%20and%20two%20workshops.
As the solution frequency increases it gives more accurate response(size of tetrahedral become small and solution is calculated on more no of points).we can use solution frequency maximum up to sweep end point.
In addition to Ravi Verma 's response, I should add that a "more accurate response" is a matter of perception. HFSS uses adaptive meshing, so it refines the mesh selectively in accordance with some criteria -- for example, in areas with higher field strengths. However, these locations may (and usually do) change with frequency, since the spectrum of modes supported by the structure (and/or excited by your ports) is frequency-dependent.
So, the resulting mesh will be refined depending on the modal field distributions of your structures/excitations at each frequency. Some modes that you are interested in may be present at some frequencies, but not at others -- for this reason, you really do need to select the solution frequencies carefully.
Stuart Barth Ravi Verma thank you for your replies. I am able to understand from your answers that solution frequency has a role in forming mesh. My question is I am giving the same solution frequency 3GHz but I am getting different results when
I give 3GHz as solution frequency at first time- step(1)
I give 3GHz at first then 2.7GHz and then again 3GHz solution frequency-step(2)
At both step 1 and step 2 the final solution frequency given was 3GHz but the results are different.
I don't know why? Can you help me in solving this doubt.
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