sierpinski antenna

Hello guys I'm new in HFSS I've just tried some examples from this forum and a couple books. I'm doing some desings of microstrip patch antennas and I want to simulate the antenna described in "On the behavior of the sierpinbski Multi band fractal antenna" but I have some troubles.
I can not get the same return loss, If I use the ground plane of 800x800mm the simulator says that there is not enough memory, so I did a reduction. Also the feed metod is not the same, I'm using a microstrip line feeder the same used for the square antenna from the tutorial of this forum.
If some body can tell me what is the problem It'll be of great help. I did attach a word document with the specifications and the return loss from the paper and my best desing in HFSS, with this one I have a return loss similar but with a displasament in frequency.
Thankyou. :D

could you find any design formulas for this type of antenna ..... I am trying to design them but for exactly same dimentions and inset feed results are same ....

since you are working for long now .... any guidlines for these parameters?