radiation patterns in cst and hfss

Hi all
i want to know the meaning of omnidirectional radiation pattern
also i want to know how the radiation pattern can be used to find gain of antenna at a particular frequency in hfss and cst mws
kartik
i want to know are these normalized radiation patterms w.r.to what

Wikipedia has an entry for that:
http://en.wikipedia.org/wiki/Omnidirectional_antenna
The simulation software can show you the gain, so don't need them calculate by yourself.
The gain is usually stated in dB or dBi, thus is normalized to an isotropic radiator.
http://en.wikipedia.org/wiki/Isotropic_antenna