Dipole Antenna Impedance Simulation in HFSS

[Potatoze]

Hello,

I simulated a dipole antenna in HFSS but the resulted impedance is not as expected as the ideal value. The antenna is made of two straight metal lines, with a rectangular in between, as in the picture.

The S11 has greatest loss at 920MHz, and the corresponding impedance is around 70-5j ohms. The real part of the impedance is close to the ideal 73 ohms, but t the imaginary part is way off the 42j ohms. I'm wondering if this is normal in HFSS simulation, or I made something wrong?

Thanks.

 

[PlanarMetamaterials]

and the corresponding impedance is around 70-5j ohms. The real part of the impedance is close to the ideal 73 ohms, but t the imaginary part is way off the 42j ohms.

I'm not understanding this, from your description and data you have 5 or 4.6 Ohms of reactance, where did 42j come from?