CST simulation error

hi all,
Anyone know how to solve as attachment error?
My S11 looks very weird when I just change the material properties PEC by edit the epsilon and loss tangent.
kindly help, urgent
regards,
leekyg

Can you post what you are simulating and how?

Dear leekyg
always when you set the frequency range in CST do not start with (0) zero, for example start at 0.5 GHz.

It doesn't matter, cst only interpolates to 0Hz