A qustion about antenna efficiency calculated in HFSS!

hello ,everyone. Recently I have used HFSS to simulate two kinds of antenna (helical and microstrip antenna),I found all the parameters like gain ,directivity,pattern are correct except the antenna efficiency ,which is always highter than 1.
I was quite puzzled that it was obviously unreasonable for efficiency highter than 1,did Ansoft HFSS use another kind of defination,or I made some mistake?????

thank you in advance!

excuse my poor english :)

no one help me ??????
please!!!!!!!!!!!!!!!!!!!!!!!!!!

There has been a discussion on this before in this board. See https://www.edaboard.com/viewtopic.php?t=95370

-svarun

I'm not sure if my reply is applicable, or it may form another discussion, or I may infact be talking rubbish. But being a much practical person who uses simulation tools occasionally, I THINK I was told that some people would calculate efficiency using the:

efficiency = (Gain of measured AUT / Gain of simulated AUT)*100%

Do let me know if I'm wrong.

Best regards,
David