I am simulating a waveguide antenna in both HFSS and CST. In HFSS, there are multiple options to plot the Gain for 3d polar plot (Abs, dB, dBm, and dBi). At first I only plotted with dB, but now, new simulations are showing the previous dB pattern in Abs, while the dB plot pattern has shifted. This issue has also been observed in Cartesian plots as well. How to address this problem?
It makes no difference which gain parameter you use, as long as you know what it means and how to use it. It seems that you may not know what any of these mean. Abs will be a linear measure of size that will never be negative. It may be either power or amplitude (square root of power). Find out which, either from the help or by doing predictions where you know what the answer should be. dB is the log of a ratio, but only within that set of data, so tells you nothing about how the result compares to other results in size, dBm is the log of the ratio to a milliwatt, and dBi is the log of the ratio to the gain of an isotropic antenna (one that radiates equally in all directions, its gain is 1).
Thankyou very much Malcolm White for your response.
Yes I am basically trying to simulate to achieve gain to measure the beamwidth of the antenna. The paper followed has ambiguities of not following one set of gain parameters. dBi and dbm are not regarded, as the antenna is not isotropic. only dB was was considered because of its standard logarithmic value. After some simulations with secondary designs, the benchmark antenna suddenly changed its results without any change in its design parameters. Is this related to any simulation error?
I can not tell from what you have said what is going wrong. You do not seem to have understood what I said. If what you want is the beamwidth then any of the formats will be suitable, provided that you understand them.
When you say the benchmark antenna changed its results do you mean the performance changed or that the way it was displayed changed?
Dear Sir Malcolm White ,
My benchmark file simulation results, without resimulating, changed its display results. While I was following those parameters previously, the new results of seperate file also followed a similar behaviour after simulation. This prompted me to check other Gain parameters like Abs as well. I crosschecked with CST results, and it gave somewhat similar solutions to my original results, even though it follows finite integration method. Can this be attributed to any bug in HFSS?
All of the gain parameters in HFSS are true but have different meanings.
you should know which of them is useful for your application.
I'm agree with Vahid Jamshidiha. You have to choose which parameter is the most significant for your application.
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