patch antenna radiation efficiency in cst

after i simulate in farfield result ,3d view i see rad.eff=-1.173db and total rad.eff=-1.204 how i can convert these results to percent as ussually said for antennas:ex:70% efficiency

radiation efficiency = 100*10^(-1.173/10) = 76%. If this is an electrically small antenna, this is a good figure.

many thanks it realy help.

many thanks for your valuable help do u know answer of this thread: https://www.edaboard.com/thread309714.html

sorry what is the formula of calculating radiation efficiency?