Negative real impedance? (HFSS design)

[lechko]

Hi everyone, im new to this group so i hope you can help me...
I've been working with HFSS for a while now, designing RF coils for MRI. The structure is pretty simple - a single turn coil with a coax feed. the feed is blocked by a copper block on its port end, and the inner coax connects to the coil... (coil radius=7cm) the problem is that i keep getting negative real part for my impedance in low freq. (around 100MHz).
Happend to any of you? what's that supposed to mean in HFSS?

thanks in advance
Alex

 

[asdfaaa]

Hi everyone, im new to this group so i hope you can help me...
I've been working with HFSS for a while now, designing RF coils for MRI. The structure is pretty simple - a single turn coil with a coax feed. the feed is blocked by a copper block on its port end, and the inner coax connects to the coil... (coil radius=7cm) the problem is that i keep getting negative real part for my impedance in low freq. (around 100MHz).
Happend to any of you? what's that supposed to mean in HFSS?

thanks in advance
Alex

Still can not understand the structure, if you can post a figure, it may be helpful for understanding.

Regards,