best software for Er 45 subst MS ant (cst，hfss) ， TD or FD?

best software for Er 45 subst MS ant (cst,hfss) , TD or FD?
i am trying to build a miniature microstrip GPS antenna with Er 45,90 .
which simulation will be best for Er 45 or 90 substrate microstrip antenna ?
time domaine or frequency domaine (for the best accurate result and minimum time simulation ).

Hi, bbvv:
You can try our IE3D EM Simulator on it. IE3D has been verified to work with Er as high as 1000. Please download a free evaluation license from www.zeland.com and give it a try. I am Jian from Zeland. Regards.

Hi,
it's hard to know if TD or FD performs better before you actually try. I guess it depends on more the just the dielectric const. Other factors are the complexity of the model. Would you like to included some parts of the GPS receiver (handheld?) has well? In my experience with high dielectric antennas I have noticed that modeling the finite GND planes and sometimes even the attached cable become important because not only the the antenna but the entire assembly starts to become the radiator.
From this point of few I would use CST. Here you have the choice between FD and TD.
F.