I'm simulating a patch atenna. It simple to use the optimizer for finding the feeding point for a perfect match at the resonance frequency. But is there a way of also optimizing the antenna for maximum bandwidth? If the antenna height and dielectric is chosen, then the bandwidth is proportional to the width/length ratio. So one needs to maximize the width.
What I would suggest you to do is to define the goal as S(1,1) < -10 dB over a wide frequency range. IE3D should try to optimize the structure for the goal you want.