Why not take some formula, generate layout and do 2d/3d simulation over some range of input parameters, use criteria to find good solution?
For single patch antenna with fed on one side: for frequency F vary W,H: W=1mm to 100mm, H=1mm to 100mm. Delta=0.001mm. Find best radiation pattern, S11, etc.
For fractal antenna: for frequency F take formula, vary formula parameters with some Delta. Generate layout for each iteration, Find best radiation patterm, S11, etc.