Why Am I Seeing a Sudden Change in S-Parameters at 3.5 GHz for intelligent reflecting surface( IRS/RIS) in CST Studio ?

[Mahendra_3]

Hi everyone,

I’m working on an Intelligent Reflecting Surface (IRS/RIS/metasurface) in CST Studio, and I'm seeing a sudden change in S-parameters at my resonance frequency (3.5 GHz). This doesn’t match the smooth transition from 180 to -180 degrees reported in many IEEE papers. mean while some paper has the same graph as mine.

Additionally, are there any processes to bias the IRS in CST? I’ve attached a graph showing the S-parameters for reference.

 

[BradtheRad]

In fact the rightmost graph appears to show a smooth transition from 180 to -180 degrees. It's mathematically correct even though it looks dog-legged. I guess there's no other correct way to plot all test results in one graph.