HFSS antenna simulation setup in THz

Hello,

I am trying to design antenna on HFSS, and I interested in 1-150 THz frequency range. While I setup driven modal simulation, on some frequencies, the efficiency of antenna has larger values than 1 (incident power is lower than radiated power).

I tried to increase the radiation boundary, but it did not work (I increased it up to 150 μm - there is no change and at 150 μm, the error appeared: Unable to locate or start COM engine on '...': no response from COM engine) there is still η>1. And there is no correlation between the frequencies which have efficiency more than 1 and the box size.

Has the problem caused by the excitation? Is it possible to radiate EM directly on to antenna? How can I solve those problems?

I am eagerly waiting for your solutions,

Thanks in advance.

Welcome basicdes,

The problem could be your excitation - can you proved some details? Is it a waveport? Did you normalize to a port impedance? What kind of antenna is it?

Probably, the problem has nothing to do with the airbox size. I usually get efficiency above 1 if bad (that is coarse) mesh is around a "hot" spot. Try to create a finer (denser) mesh

My excitation is given by lumped port which is meshed to 50 ohms. The antenna is 3-D micro-sized bow-tie antenna.