HFSS Far-field radiation efficiency of antenna

regards to everybody.
when simulate loop antenna on vehcle by HFSS, the far-field radiation efficiency reaches as high as 1.02?! And HFSS suggests Radiation efficiency=Radiationpower/Acceptedpower,what's the problem?
in the table of far-field what's the incident power?
thanks for any replys.

Interesting subject. Could you please share the project?

please define antenna material property correctly means matrial tangent loss specially.