Antenna efficiency goes beyoud one in HFSS simulating?

When I simulated a patch antenna with HFSS, the resulting antenna efficiency reached 1.15. It is an impossibile value in practice. Did anyone ever meet this problem? Who can tell me why this phenomenon appears, and how can I solve it? Thanks.

You may try seeding the radiation boundry yourself. There is a problem in their generated radiation info. I have found issues with phase data and lower level off axis x-pol data. The boundry seeding is what I was told to try. I havent had much time to play with it to see if its effective or not.

Also if you are trying to use a cavity below cut off you'll get some pretty odd things. HFSS does not handle that situation. It does let you design a passive waveguide structure with gain though .

Good luck, I'll be interested in knowing the out come.

H3O

I don't quite understand your meaning of "seeding the radiation boundry " Do you mean set the radiation boundry far enough to the antenna structure ? The distance between the boundry and the antenna structure is set to above 0.25 wavelength. But I got an even worse result, the efficiency goes higher than before. I don't know what's wrong with it.