radiation efficiency in HFSS

hello dear
when i simulate dielectric resoantor antenna in HFSS then the radiation efficiency of antenna is coming always greater then one means more then 100%.
plz tell me how can this happen?
radiation efficiency is always equal to or less then 100%.
plz help me......................

this usually happens when the dielectric materials are not assigned any losses. also most probably radiation boundaries are not meshed as good as the dielectrics and efficiency is calculated wrong...

thanx dear for helping me.

pls notice real efficiency which is more important in fact, and it consider return loss and other loss. hope it help!

dielectric resonator TEM and TE type from www.accutemicro.com

The topic of a simulated radiation efficiency larger than unity (100%) has appeared frequently on this forum. As far as I am aware, results obtained with Ansoft HFSS and CST MWS have been discussed. In a recent paper, simulation results for the radiation efficiency of low-loss antennas (with required efficiency of 97% or higher) are shown. These results have been obtained with 5 different simulators (Ansoft HFSS, CST MWS, Ansoft Designer, FEKO, and an in-house moment code). Explanations for the efficiency results, either lower or higher than 100%, are provided. Moreover, in the discussion on the different computational procedures for the radiation efficiency, also the simulators Zeland IE3D and Sonnet are considered. Hopefully the paper can help in the understanding of problems arsing in the simulation of the radiation efficiency of (low-loss or lossless) antennas. Data of the paper: R. Maaskant, D.J. Bekers, M.J. Arts, W.A. van Cappellen, and M.V. Ivashina, Evaluation of the Radiation Efficiency and the Noise Temperature of Low-Loss Antennas, IEEE Antennas and Wireless Propagation Letters, Vol. 8, pp. 1166 – 1170, 2009.