@anvc - This sounds like a problem with mixed units or improper setup. A simple dipole should not take more than a couple of minutes to solve. Even though the structure may be large in physical size (17 cm), it should be reasonable in electrical size (lambda/2). Check to make sure your units are correct, and that your analysis frequency is appropriate. One more thing to check is if you have any high permittivity materials surrounding your antenna. If this is the case, like with a human head (er ~ 80), then you might want to enable the checkbox next to Lambda Refinement on the options tab of the Analysis setup, that specifies to use "free space wavelength." I don't recommend using this in general, but if you have a very high permittivity object, it can sometimes help.
@sayyedjamal - I'm not sure how ADS is going to solve a 3D antenna problem. I can see where you might be able to use Momentum instead of HFSS for a filter, but the antenna is inherently 3D. Also, HFSS should do a fine job with microwave filters. If you have any problems, I suggest you contact your local ANSYS Applications Engineer for assistance.