StriplineLine

class pmrf.models.components.lines.stripline.StriplineLine(length: Any, w: Any = 0.002655, b: Any = 0.0032, t: Any = 3.5e-05, dielectric: Any = <factory>, conductor: Any = <factory>, formulation: AbstractStriplineFormulation = <factory>, current_distribution: AbstractCurrentDistribution = <factory>, *, name: str | None = None, metadata: Any = None)

Bases: AbstractImmittanceLine

Stripline defined by its geometry and material modules.

The default is CohnStriplineFormulation. Homogeneous filling gives \(\varepsilon_e=\varepsilon_r\) without a separate modal-dispersion model. Material dispersion remains available through the dielectric.

Mathematical Formulation

The quasi-static formulation returns \((\varepsilon_e, Z_c, W_{eff})\), and PlanarQuasiStaticResult.to_immittance() converts them directly:

\[Z = \frac{j\omega Z_c\sqrt{\varepsilon_e}}{c} + \frac{2Z_s}{W_{eff}} \qquad Y = \frac{j\omega\sqrt{\varepsilon_e}}{Z_c c}.\]

See CohnStriplineFormulation for the geometry.

Example

import pmrf as prf
from pmrf.models import StriplineLine
from pmrf.materials import BulkConductor, ConstantDielectric

line = StriplineLine(
    w=2.655e-3,
    b=3.2e-3,
    t=35e-6,
    dielectric=ConstantDielectric(ep_r=2.2, tand=0.001),
    conductor=BulkConductor(sigma=5.8e7),
    length=0.1,
)

freq = prf.Frequency(start=1, stop=20, npoints=101, unit='ghz')
s = line.s(freq)

Parameters:

w (Param, default=2.655e-3) – Width of the centre strip in meters.
b (Param, default=3.2e-3) – Separation of the ground planes in meters.
t (Param | None, default=35e-6) – Thickness of the centre strip in meters. None idealises it as zero-thickness, which has no finite conductor loss.
dielectric (AbstractDielectric, default=ConstantDielectric(ep_r=4.3)) – The filling between the ground planes. A scalar permittivity or an (ep_r, tand) tuple is coerced into a ConstantDielectric.
conductor (AbstractConductor, default=BulkConductor()) – The material of the strip and the ground planes. A scalar conductivity in S/m is coerced into a BulkConductor.
formulation (AbstractStriplineFormulation, default=CohnStriplineFormulation()) – The closed-form physics used to compute the quasi-static solution.

References

Cohn, S. B. (1955). Problems in Strip Transmission Lines. IRE Transactions on Microwave Theory and Techniques, 3(2), 119-126.

Pozar, D. M. (2011). Microwave Engineering (4th ed.), Section 3.7. Wiley.

immittance(freq: Frequency) → ImmittanceResult

Calculates the frequency-dependent per-unit-length immittance.

Parameters:: freq (Frequency) – The frequency axis.
Returns:: The series impedance and shunt admittance vectors.
Return type:: ImmittanceResult

b: Param = 0.0032: Separation of the ground planes

conductor: AbstractConductor: The material of the strip and the ground planes

current_distribution: AbstractCurrentDistribution: The conductor current-distribution strategy

dielectric: AbstractDielectric: The filling between the ground planes

formulation: AbstractStriplineFormulation: The underlying physics formulation

t: Param | None = 3.5e-05: Thickness of the centre strip

w: Param = 0.002655: Width of the centre strip