flex_rf.tidy3d.HammerstadSurfaceRoughness
Type: class │ Base(s): AbstractSurfaceRoughness
Description
Section titled “Description”Modified Hammerstad surface roughness model. It’s a popular model that works well under 5 GHz for surface roughness below 2 micrometer RMS.
The power loss compared to smooth surface is described by:
where is skin depth, the RMS peak-to-vally height, and RF roughness factor.
This model is based on:
Y. Shlepnev, C. Nwachukwu, “Roughness characterization for interconnect analysis”, 2011 IEEE International Symposium on Electromagnetic Compatibility, (DOI: 10.1109/ISEMC.2011.6038367), 2011.
V. Dmitriev-Zdorov, B. Simonovich, I. Kochikov, “A Causal Conductor Roughness Model and its Effect on Transmission Line Characteristics”, Signal Integrity Journal, 2018.
Parameters
Section titled “Parameters”rq [PositiveFloat] |
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RMS peak-to-valley height (Rq) of the surface roughness. |
roughness_factor [float] = 2.0 |
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Expected maximal increase in conductor losses due to roughness effect. Value 2 gives the classic Hammerstad equation. |
Methods
Section titled “Methods”roughness_correction_factor(frequency: ArrayFloat1D, skin_depths: ArrayFloat1D) |
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Complex-valued roughness correction factor applied to surface impedance. |