RF Material Models

RF and microwave simulations often need metal models, lossy dielectrics, and frequency-aware material fits. Flex RF exposes the relevant material classes through flex_rf.tidy3d.

Metal Models

Use PECMedium for lossless perfect conductors and LossyMetalMedium for surface-impedance lossy metals.

from flex_rf.tidy3d import LossyMetalMedium, PECMedium

my_pec = PECMedium()

my_lossy_metal = LossyMetalMedium(
    conductivity=58,
    freq_range=(1e9, 10e9),
)

LossyMetalMedium uses a surface impedance boundary condition. It can also use surface roughness specifications such as HammerstadSurfaceRoughness and HuraySurfaceRoughness.

Check skin depth before using a surface-impedance metal. If the skin depth is large compared with the geometry scale, use a regular dispersive medium instead of LossyMetalMedium.

Dielectric Models

Use Medium for lossless dielectrics.

from flex_rf.tidy3d import Medium

my_lossless_dielectric = Medium(permittivity=2.2)

For a lossy dielectric with constant loss tangent, use constant_loss_tangent_model.

from flex_rf.tidy3d import constant_loss_tangent_model

my_lossy_dielectric = constant_loss_tangent_model(
    eps_real=4.4,
    loss_tangent=0.002,
    frequency_range=(1e9, 5e9),
)

More advanced material models include frequency dependence, anisotropy, custom spatial data, pole-residue fits, and 2D media.

Related API Symbols

Symbol	Purpose
PECMedium	Perfect electric conductor medium.
PMCMedium	Perfect magnetic conductor medium.
LossyMetalMedium	Surface-impedance lossy metal model.
SurfaceImpedanceFitterParam	Advanced fitting parameters for surface impedance.
Medium	Basic nondispersive medium.
PoleResidue	Dispersive medium represented by pole-residue terms.
CustomMedium	Spatially varying material model.
rf_material_library	Library of common RF material fits.

Related Pages

Page	Why open it
RF Material Library	Load common RF materials by library key and variant.
Layer-Based Grid Refinement	Refine grids near metallic corners and planar layers.