Hi, Micro_tech:
No matter whether an antenna is high-Q or low-Q, you can always tune it to get VSWR < 2.
On IE3D, you can find the radiation patterns. From the radiation patterns, you can find the radiation efficiency (ratio between radiated power and net input power). It is the most important factor for determinng how good the antenna is radiating. For VSWR or RL, you check the S(1,1). Low RL means that there is little reflected power back from the antenna. It does not mean the radiation efficiency is high. However, for most antennas, when the basic shapes are fixed, changes of dimensions normally may not affect the radiation efficiency much. However, it will affect the VSWR or RL much. In such a situation, you just check VSWR and RL when you tune the antenna. When you get VSWR < 2 or RL < 10%, it may mean you are getting kind of the best from such a configuration. However, where it is good or not good, you still need to check the radiation efficiency. Regards.