Best sweep that gives good agreement between simulation and measurement is "Discrete", but to avoid long time simulation, "Fast" sweep gives a good estimate till you reach optimum parameters, then confirm the optimum parameters with "Discrete" sweep.

Ahmed Abdelraheem thank you for your answer.

I did exactly what you mentioned.

Problem came at the difference when i went for discrete after completing fast sweep.

Do you have any permanent solution for this. Or, should i go for discrete every time i carry out the simulation?

As far as I know, fast sweep shouldn't differ that much from discrete sweep. Please review your excitation, and boundary conditions.

If you are sure about every thing, then nothing you can do except use a powerful workstation and conduct parametric analysis.

there is some thing that may save your time, that you study the sensitivity of each parameter you need to change. This will give you a good lead to the effect of each parameter and will allow you to minimize the parametric runs.

Thanks for asking to check my mistakes. I think i am making some.

I worked with spiral antennas, and I divided the bandwidth to steps of 2 GHz and used fast sweep, Then I divided the bandwidth to the steps of 1 GHz again with fast sweep.

For frequencies bellow 10 GHz the first sweep was reasonable but the second one gave me results that agreed with the measurements.

So I found the narrower steps in solution bands would be better !

I did that before with a CPW monopole and it gave almost the same results as one whole bandwidth !!

Ahmed Deel , did you do that on different setups or different sweeps under the same setup ?

when I simulated spiral antenna, the mesh structure for lower frequencies was big and the inner parts of spiral didn't need too much mesh; but then mesh structure for higher frequencies was small and the outer parts of spiral, despite the current on those parts was small and negligible, was meshed so densely that computational space requirement was more than my RAM.

Using a center frequency and one frequency setup in my simulation didn't give good results because its mesh was not proper for higher frequencies and inner parts.

So I got good results with dividing the wide-bandwidth into small ones.

As per my experience, 1-GHz to 6GHz can give best results in HFSS, but exactly known about engineering of an antenna.

Interpolating Sweeps is used for a very broadband  frequency sweep i.e. maxfreq/minfreq > 4. Only drawback is it doesn't produces field solution in a specific frequency.

Fast sweep should be default sweep as long as maxfreq/minfreq < 4.

In Discrete sweep the simulation time is proportional to the number of frequency points specified. It is used to calculate fields after doing an interpolating sweep.

It doesn't matters which sweep type you have choosen your results should be same for all.

for wide band antenna, 1-5GHz swept frequency find good results in HFSS, for more range simulation may arise some error.

hallo everyone...

Im also new with HFSS and working on package simulations.

im also getting Problem with frequency sweep,

can one tell me, either LogScale is better or discreat scale is better ??

Any difference in the results ??

Thanks

 For fast sweep you should widen your operation frequency band by 25%.

Airbox size should be defined on Fmin.

why in time domain measurement in HFSS mutual couplings are not calculated? I mean S21, S31, S41, etc are not shown in results?