how to plot antenna gain vs frequency in dbi using HFSS

i am learning hfss, please help me to plot antenna gain vs frequency in dbi directly.

HFSS 3 have only following unit
db,
dbm,
dbwm,
dbc

then how to plot in dbi, help me!

dBi is the Gain (in dB) of you antenna related to that an isotropic radiator (which.... doesn't exist in practice).

I believe you can simply consider the Gain in dB you get in HFSS as if it were in dBi.

On the other hand:
- dBm and dBW are relative to Power (not Gain)
- dBc stands for decibels below the carrier (it is used to define the sideband noise properties of oscillators)

Gain dB = Gain dBi

For plotting the gain over frequency you need to make a frequency sweep and activate the "save field" option. Then you select under plot Far Fields Reports -> Rectangular plot. Now you can plot the gain versus the frequency.