Waveguide material parameter extraction

[Kevin]

Hello,

Has anyone used the waveguide material parameter extraction feature? I tested it out with a simulated short waveguide section (no material, just air), and the calculated relative permittivity was not 1. Also tried with PTFE, and results were also way off. I am giving it S-parameters, length, and cutoff frequency.

Any help would be greatly appreciated.

Thanks,

Kevin

[Michael Wollensack METAS]

Hi,

can you provide a minimum example (simulation data and the expectation you have).

Regards

Michael

[Kevin]

Hi Michael,

Thank you for your response.

Attached is one .s2p file I'm working with. It's 5 mm of WR-90, with nothing inside (relative permittivity & permeability = 1).

The plots below from METAS VNA Tools are using the NRW algorithm (black) and Direct algorithm (red).

As you can see, the NRW option is miscalculating both parameters. Direct is working in this most basic case, but becomes inaccurate when I test with a material with εr = 2,  µr = 1.

Best Regards,

Kevin