Characteristic modes sorting in CST

I want to simulate a dual band antenna using CST MWS. I'm using the Multilayer solver. When Multilayer solver setup window appears, it asks to indicate a frequency for mode sorting. Which frequency for sorting i should use since i've a dual band antenna?

Posting recommendation from CST help
If the number of modes of interest in the simulation frequency range is unknown, start the analysis with a small number of requested modes, e.g., 3 to 5, and repeat the analysis with different frequencies for mode sorting fSort. For instance, perform one analysis with fSort = fMin and another one with fSort = fMax). If the found modes are different, repeat the analysis with a value of fSort in between. This way, the risk of omitting a characteristic mode of interest due to an unfortunate choice of fSort is minimized. Moreover, running multiple analyses with a small number of requested modes may be faster than performing one analysis with a larger number of requested modes.
in case you found some answer then please update