diff --git a/GridKit/Model/EMT/Parameters/Effects/Carson/README.md b/GridKit/Model/EMT/Parameters/Effects/Carson/README.md
new file mode 100644
index 000000000..51b828f00
--- /dev/null
+++ b/GridKit/Model/EMT/Parameters/Effects/Carson/README.md
@@ -0,0 +1,117 @@
+# Carson Model
+
+`Carson` computes frequency-dependent earth-return resistance and inductance
+matrices for overhead conductors using the Deri-Semlyen approximation to
+Carson's homogeneous-earth return term.
+
+## Model Parameters
+
+Symbol | Units | JSON | Description | Note
+------ | ----- | ---- | ----------- | ----
+`tower` | [-] | - | Static conductor tower | [`Tower`](../../Geometry/Tower/README.md)
+$\sigma_g$ | [S/m] | `earth_conductivity` | Earth conductivity | $\sigma_g\ge0$
+$\varepsilon_g$ | [F/m] | `earth_permittivity` | Earth permittivity | $\varepsilon_g\ge\varepsilon_0$
+$\mu_0$ | [H/m] | - | Vacuum permeability | constant
+$\varepsilon_0$ | [F/m] | - | Vacuum permittivity | constant
+
+### Parameter Validation
+
+```math
+\sigma_g\ge0,\qquad
+\varepsilon_g\ge\varepsilon_0,\qquad
+\omega > 0,\qquad
+(\gamma_g^{\mathrm r})^2+(\gamma_g^{\mathrm i})^2 > 0
+```
+
+The connected tower model owns its geometry validation.
+
+### Model Derived Parameters
+
+For conductor pair $(i,j)$,
+
+```math
+\begin{aligned}
+d_{ij} &= |x_i-x_j| \\
+s_{ij} &= h_i+h_j \\
+\Delta_g &= (\gamma_g^{\mathrm r})^2+(\gamma_g^{\mathrm i})^2 \\
+p^{\mathrm r} &= \frac{\gamma_g^{\mathrm r}}{\Delta_g} \\
+p^{\mathrm i} &= -\frac{\gamma_g^{\mathrm i}}{\Delta_g} \\
+H_{ij}^{\mathrm r} &= s_{ij}+2p^{\mathrm r} \\
+H_{ij}^{\mathrm i} &= 2p^{\mathrm i} \\
+A_{ij} &= d_{ij}^2+(H_{ij}^{\mathrm r})^2-(H_{ij}^{\mathrm i})^2 \\
+B_{ij} &= 2H_{ij}^{\mathrm r}H_{ij}^{\mathrm i} \\
+M_{ij} &= A_{ij}^2+B_{ij}^2 \\
+\theta_{ij} &= \operatorname{atan2}(B_{ij},A_{ij}) \\
+\Lambda_{ij} &= \frac{1}{4}\ln M_{ij}-\ln D'_{ij}
+\end{aligned}
+```
+
+## Model Variables
+
+### Internal Variables
+
+#### Differential
+
+None.
+
+#### Algebraic
+
+Symbol | Units | Description | Note
+------ | ----- | ----------- | ----
+$\eta_g$ | [1/m$^2$] | Magnitude of earth-return propagation radicand | real
+$\gamma_g^{\mathrm r}$ | [1/m] | Real earth-return propagation constant component | real
+$\gamma_g^{\mathrm i}$ | [1/m] | Imaginary earth-return propagation constant component | real
+$\mathbf{R}^{\mathrm{carson}}$ | [$\Omega$/m] | Carson earth-return resistance | $\mathbb{R}^{K\times K}$
+$\mathbf{L}^{\mathrm{carson}}$ | [H/m] | Carson earth-return inductance | $\mathbb{R}^{K\times K}$
+
+### External Variables
+
+#### Differential
+
+None.
+
+#### Algebraic
+
+None.
+
+## Model Equations
+
+### Differential Equations
+
+None.
+
+### Algebraic Equations
+
+```math
+\begin{aligned}
+0 &= -\eta_g^2
+ + (\omega^2\mu_0\varepsilon_g)^2
+ + (\omega\mu_0\sigma_g)^2 \\
+0 &= -2(\gamma_g^{\mathrm r})^2
+ + \eta_g - \omega^2\mu_0\varepsilon_g \\
+0 &= -2(\gamma_g^{\mathrm i})^2
+ + \eta_g + \omega^2\mu_0\varepsilon_g \\
+0 &= -4\pi R_{ij}^{\mathrm{carson}}
+ - \omega\mu_0\theta_{ij} \\
+0 &= -2\pi L_{ij}^{\mathrm{carson}}
+ + \mu_0\Lambda_{ij}
+\end{aligned}
+```
+
+## Initialization
+
+Initialize $\eta_g$, $\gamma_g^{\mathrm r}$, $\gamma_g^{\mathrm i}$,
+$\mathbf{R}^{\mathrm{carson}}$, and $\mathbf{L}^{\mathrm{carson}}$ from the
+algebraic equations at the current $\omega$.
+
+## Model Outputs
+
+Symbol | Units | Description | Note
+------ | ----- | ----------- | ----
+$\sigma_g$ | [S/m] | Earth conductivity | real
+$\varepsilon_g$ | [F/m] | Earth permittivity | real
+$\eta_g$ | [1/m$^2$] | Magnitude of earth-return propagation radicand | real
+$\gamma_g^{\mathrm r}$ | [1/m] | Real earth-return propagation constant component | real
+$\gamma_g^{\mathrm i}$ | [1/m] | Imaginary earth-return propagation constant component | real
+$\mathbf{R}^{\mathrm{carson}}$ | [$\Omega$/m] | Carson earth-return resistance | $\mathbb{R}^{K\times K}$
+$\mathbf{L}^{\mathrm{carson}}$ | [H/m] | Carson earth-return inductance | $\mathbb{R}^{K\times K}$
diff --git a/GridKit/Model/EMT/Parameters/Effects/GeometricInductance/README.md b/GridKit/Model/EMT/Parameters/Effects/GeometricInductance/README.md
new file mode 100644
index 000000000..8a93b1647
--- /dev/null
+++ b/GridKit/Model/EMT/Parameters/Effects/GeometricInductance/README.md
@@ -0,0 +1,78 @@
+# GeometricInductance Model
+
+`GeometricInductance` computes the external geometric series inductance matrix
+for the physical conductors.
+
+## Model Parameters
+
+For $K$ physical conductors:
+
+Symbol | Units | Description | Note
+------ | ----- | ----------- | ----
+`tower` | [-] | Static conductor tower | [`Tower`](../../Geometry/Tower/README.md)
+`conductor` | [-] | Static conductor data | [`Conductor`](../../Geometry/Conductor/README.md)
+$\mu_0$ | [H/m] | Vacuum permeability | constant
+
+### Parameter Validation
+
+The tower and conductor models must pass their own validation.
+
+### Model Derived Parameters
+
+The tower model provides $h_i$, $D_{ij}$, and $D'_{ij}$. The conductor model
+provides $r_i$.
+
+```math
+\left(\boldsymbol{\Lambda}^{\mathrm{geo}}\right)_{ij} =
+\begin{cases}
+\ln\dfrac{2h_i}{r_i}, & i=j \\
+\ln\dfrac{D'_{ij}}{D_{ij}}, & i\ne j
+\end{cases}
+```
+
+## Model Variables
+
+### Internal Variables
+
+#### Differential
+
+None.
+
+#### Algebraic
+
+Symbol | Units | Description | Note
+------ | ----- | ----------- | ----
+$\mathbf{L}^{\mathrm{geo}}$ | [H/m] | External geometric inductance | $\mathbb{R}^{K\times K}$
+
+### External Variables
+
+#### Differential
+
+None.
+
+#### Algebraic
+
+None.
+
+## Model Equations
+
+### Differential Equations
+
+None.
+
+### Algebraic Equations
+
+```math
+\mathbf{0} = -2\pi\mathbf{L}^{\mathrm{geo}}
+ + \mu_0 \boldsymbol{\Lambda}^{\mathrm{geo}}
+```
+
+## Initialization
+
+None beyond the static tower and conductor initialization.
+
+## Model Outputs
+
+Symbol | Units | Description | Note
+------ | ----- | ----------- | ----
+$\mathbf{L}^{\mathrm{geo}}$ | [H/m] | External geometric inductance | $\mathbb{R}^{K\times K}$
diff --git a/GridKit/Model/EMT/Parameters/Effects/InsulatorLeakage/README.md b/GridKit/Model/EMT/Parameters/Effects/InsulatorLeakage/README.md
new file mode 100644
index 000000000..31446451a
--- /dev/null
+++ b/GridKit/Model/EMT/Parameters/Effects/InsulatorLeakage/README.md
@@ -0,0 +1,71 @@
+# InsulatorLeakage Model
+
+`InsulatorLeakage` computes an empirical direct shunt conductance effect for
+the physical conductors.
+
+## Model Parameters
+
+For $K$ physical conductors:
+
+Symbol | Units | JSON | Description | Note
+------ | ----- | ---- | ----------- | ----
+$g_i^{\mathrm{leak}}$ | [S/m] | `leakage_conductance` | Insulator leakage conductance to ground | $g_i^{\mathrm{leak}}\ge0$
+
+### Parameter Validation
+
+```math
+g_i^{\mathrm{leak}}\ge0,\qquad i=1,\dots,K
+```
+
+### Model Derived Parameters
+
+For a vector $\mathbf a\in\mathbb{R}^K$, let
+$\operatorname{diag}(\mathbf a)$ denote the diagonal matrix with $\mathbf a$ on
+the main diagonal.
+
+## Model Variables
+
+### Internal Variables
+
+#### Differential
+
+None.
+
+#### Algebraic
+
+Symbol | Units | Description | Note
+------ | ----- | ----------- | ----
+$\mathbf{G}^{\mathrm{leak}}$ | [S/m] | Insulator leakage shunt conductance | diagonal
+
+### External Variables
+
+#### Differential
+
+None.
+
+#### Algebraic
+
+None.
+
+## Model Equations
+
+### Differential Equations
+
+None.
+
+### Algebraic Equations
+
+```math
+\mathbf{0} = -\mathbf{G}^{\mathrm{leak}}
+ + \operatorname{diag}(\mathbf{g}^{\mathrm{leak}})
+```
+
+## Initialization
+
+Validate the leakage conductance vector.
+
+## Model Outputs
+
+Symbol | Units | Description | Note
+------ | ----- | ----------- | ----
+$\mathbf{G}^{\mathrm{leak}}$ | [S/m] | Insulator leakage shunt conductance | $\mathbb{R}^{K\times K}$
diff --git a/GridKit/Model/EMT/Parameters/Effects/README.md b/GridKit/Model/EMT/Parameters/Effects/README.md
new file mode 100644
index 000000000..04fbe9446
--- /dev/null
+++ b/GridKit/Model/EMT/Parameters/Effects/README.md
@@ -0,0 +1,37 @@
+# Effect Models
+
+`Effects` contains the physical effect models that assemble full-conductor
+per-unit-length overhead-line data:
+
+```math
+\mathbf{R}'(\omega),\quad \mathbf{L}'(\omega),\quad
+\mathbf{G}'(\omega),\quad \mathbf{C}'(\omega)
+```
+
+These models are frequency-domain parameter models, not EMT network components.
+They consume geometry, conductor, and earth data and produce algebraic signals
+for the response models. They are evaluated at the current system parameter
+$\omega$; sweep endpoints, sampling, and linear or logarithmic grids belong to
+the application or study driver.
+
+Model | Description
+----- | -----------
+[`SeriesImpedance`](SeriesImpedance/README.md) | Builds full-conductor per-unit-length series resistance and inductance
+[`GeometricInductance`](GeometricInductance/README.md) | Computes external geometric inductance entries
+[`SkinEffect`](SkinEffect/README.md) | Computes conductor-internal skin-effect resistance and inductance entries
+[`ShuntAdmittance`](ShuntAdmittance/README.md) | Builds full-conductor per-unit-length shunt conductance and capacitance
+[`ShuntPotential`](ShuntPotential/README.md) | Computes potential-derived zero conductance and capacitance
+[`InsulatorLeakage`](InsulatorLeakage/README.md) | Computes direct shunt leakage conductance
+[`Carson`](Carson/README.md) | Computes Carson earth-return resistance and inductance entries
+
+## Assembly
+
+Output | Built From
+------ | ----------
+$\mathbf{R}'$ | Internal skin-effect resistance and Carson earth-return resistance
+$\mathbf{L}'$ | Internal skin-effect inductance, geometric inductance, and Carson earth-return inductance
+$\mathbf{G}'$ | Shunt potential terms and optional direct leakage terms
+$\mathbf{C}'$ | Shunt potential terms
+
+The aggregate [`Overhead`](../README.md#overhead-aggregate) model wires these
+effect outputs into the response models.
diff --git a/GridKit/Model/EMT/Parameters/Effects/SeriesImpedance/README.md b/GridKit/Model/EMT/Parameters/Effects/SeriesImpedance/README.md
new file mode 100644
index 000000000..85873fe65
--- /dev/null
+++ b/GridKit/Model/EMT/Parameters/Effects/SeriesImpedance/README.md
@@ -0,0 +1,93 @@
+# SeriesImpedance Model
+
+`SeriesImpedance` builds the full-conductor per-unit-length series resistance
+and inductance matrices for one angular frequency.
+
+## Model Parameters
+
+None. `SeriesImpedance` combines effect-model outputs for $K$ physical
+conductors.
+
+### Parameter Validation
+
+None.
+
+### Model Derived Parameters
+
+For a vector $\mathbf a\in\mathbb{R}^K$, let
+$\operatorname{diag}(\mathbf a)$ denote the diagonal matrix with $\mathbf a$ on
+the main diagonal.
+
+## Model Variables
+
+### Internal Variables
+
+#### Differential
+
+None.
+
+#### Algebraic
+
+Symbol | Units | Description | Note
+------ | ----- | ----------- | ----
+$\mathbf{R}^{\mathrm{int}}$ | [$\Omega$/m] | Internal conductor resistance | diagonal
+$\mathbf{L}^{\mathrm{int}}$ | [H/m] | Internal conductor inductance | diagonal
+$\mathbf{R}^{\mathrm{ext}}$ | [$\Omega$/m] | External series resistance | full matrix
+$\mathbf{L}^{\mathrm{ext}}$ | [H/m] | External series inductance | full matrix
+$\mathbf{R}'$ | [$\Omega$/m] | Full-conductor series resistance | $\mathbb{R}^{K\times K}$
+$\mathbf{L}'$ | [H/m] | Full-conductor series inductance | $\mathbb{R}^{K\times K}$
+
+### External Variables
+
+#### Differential
+
+None.
+
+#### Algebraic
+
+Symbol | Units | Description | Note
+------ | ----- | ----------- | ----
+$\mathbf{r}^{\mathrm{skin}}$ | [$\Omega$/m] | Internal conductor resistance vector | from connected `SkinEffect` models
+$\mathbf{l}^{\mathrm{skin}}$ | [H/m] | Internal conductor inductance vector | from connected `SkinEffect` models
+$\mathbf{L}^{\mathrm{geo}}$ | [H/m] | External geometric inductance | from connected `GeometricInductance` model
+$\mathbf{R}^{\mathrm{carson}}$ | [$\Omega$/m] | Carson earth-return resistance | from connected `Carson` models
+$\mathbf{L}^{\mathrm{carson}}$ | [H/m] | Carson earth-return inductance | from connected `Carson` models
+
+## Model Equations
+
+### Differential Equations
+
+None.
+
+### Algebraic Equations
+
+```math
+\begin{aligned}
+\mathbf{0} &= -\mathbf{R}^{\mathrm{int}}
+ + \operatorname{diag}(\mathbf{r}^{\mathrm{skin}}) \\
+\mathbf{0} &= -\mathbf{L}^{\mathrm{int}}
+ + \operatorname{diag}(\mathbf{l}^{\mathrm{skin}}) \\
+\mathbf{0} &= -\mathbf{R}^{\mathrm{ext}}
+ + \mathbf{R}^{\mathrm{carson}} \\
+\mathbf{0} &= -\mathbf{L}^{\mathrm{ext}}
+ + \mathbf{L}^{\mathrm{geo}}
+ + \mathbf{L}^{\mathrm{carson}} \\
+\mathbf{0} &= -\mathbf{R}'
+ + \mathbf{R}^{\mathrm{int}}
+ + \mathbf{R}^{\mathrm{ext}} \\
+\mathbf{0} &= -\mathbf{L}'
+ + \mathbf{L}^{\mathrm{int}}
+ + \mathbf{L}^{\mathrm{ext}}
+\end{aligned}
+```
+
+## Initialization
+
+None.
+
+## Model Outputs
+
+Symbol | Units | Description | Note
+------ | ----- | ----------- | ----
+$\mathbf{R}'$ | [$\Omega$/m] | Full-conductor series resistance | $\mathbb{R}^{K\times K}$
+$\mathbf{L}'$ | [H/m] | Full-conductor series inductance | $\mathbb{R}^{K\times K}$
diff --git a/GridKit/Model/EMT/Parameters/Effects/ShuntAdmittance/README.md b/GridKit/Model/EMT/Parameters/Effects/ShuntAdmittance/README.md
new file mode 100644
index 000000000..0d06b70eb
--- /dev/null
+++ b/GridKit/Model/EMT/Parameters/Effects/ShuntAdmittance/README.md
@@ -0,0 +1,91 @@
+# ShuntAdmittance Model
+
+`ShuntAdmittance` builds the full-conductor per-unit-length shunt conductance
+and capacitance matrices from connected shunt-effect outputs. Potential-derived
+conductance is zero; direct shunt losses are represented explicitly and set to
+zero until a leakage model is wired.
+
+## Model Parameters
+
+None. `ShuntAdmittance` combines effect-model outputs for $K$ physical
+conductors.
+
+### Parameter Validation
+
+None.
+
+### Model Derived Parameters
+
+None.
+
+## Model Variables
+
+### Internal Variables
+
+#### Differential
+
+None.
+
+#### Algebraic
+
+Symbol | Units | Description | Note
+------ | ----- | ----------- | ----
+$\mathbf{G}^{\mathrm{ext}}$ | [S/m] | Direct shunt conductance effects | $\mathbb{R}^{K\times K}$
+$\mathbf{C}^{\mathrm{ext}}$ | [F/m] | Direct shunt capacitance effects | $\mathbb{R}^{K\times K}$
+$\mathbf{G}'$ | [S/m] | Full-conductor shunt conductance | $\mathbb{R}^{K\times K}$
+$\mathbf{C}'$ | [F/m] | Full-conductor shunt capacitance | $\mathbb{R}^{K\times K}$
+
+### External Variables
+
+#### Differential
+
+None.
+
+#### Algebraic
+
+Symbol | Units | Description | Note
+------ | ----- | ----------- | ----
+$\mathbf{G}^{\mathrm{pot}}$ | [S/m] | Potential-derived shunt conductance | zero matrix from connected `ShuntPotential` model
+$\mathbf{C}^{\mathrm{pot}}$ | [F/m] | Potential-derived shunt capacitance | from connected `ShuntPotential` model
+
+## Model Equations
+
+### Differential Equations
+
+None.
+
+### Algebraic Equations
+
+```math
+\begin{aligned}
+\mathbf{0} &= -\mathbf{G}^{\mathrm{ext}} \\
+\mathbf{0} &= -\mathbf{C}^{\mathrm{ext}} \\
+\mathbf{0} &= -\mathbf{G}'
+ + \mathbf{G}^{\mathrm{pot}}
+ + \mathbf{G}^{\mathrm{ext}} \\
+\mathbf{0} &= -\mathbf{C}'
+ + \mathbf{C}^{\mathrm{pot}}
+ + \mathbf{C}^{\mathrm{ext}}
+\end{aligned}
+```
+
+## Initialization
+
+The direct shunt-effect terms are initialized to zero. The assembled matrices
+are initialized from the connected `ShuntPotential` output:
+
+```math
+\begin{aligned}
+\mathbf{G}^{\mathrm{ext}} &= \mathbf{0} \\
+\mathbf{C}^{\mathrm{ext}} &= \mathbf{0} \\
+\mathbf{G}' &= \mathbf{G}^{\mathrm{pot}} \\
+\mathbf{C}' &= \mathbf{C}^{\mathrm{pot}}
+\end{aligned}
+```
+
+## Model Outputs
+
+Symbol | Units | Description | Note
+------ | ----- | ----------- | ----
+$\mathbf{G}'$ | [S/m] | Full-conductor shunt conductance | $\mathbb{R}^{K\times K}$
+$\mathbf{C}'$ | [F/m] | Full-conductor shunt capacitance | $\mathbb{R}^{K\times K}$
diff --git a/GridKit/Model/EMT/Parameters/Effects/ShuntPotential/README.md b/GridKit/Model/EMT/Parameters/Effects/ShuntPotential/README.md
new file mode 100644
index 000000000..da5bda389
--- /dev/null
+++ b/GridKit/Model/EMT/Parameters/Effects/ShuntPotential/README.md
@@ -0,0 +1,92 @@
+# ShuntPotential Model
+
+`ShuntPotential` computes the real overhead-line potential-coefficient matrix
+and the corresponding full-conductor shunt capacitance. The potential-derived
+conductance is set to zero; direct shunt losses are added by separate passive
+shunt models.
+
+TODO: high frequnecy earth return correction
+
+## Model Parameters
+
+For $K$ physical conductors:
+
+Symbol | Units | Description | Note
+------ | ----- | ----------- | ----
+`tower` | [-] | Static conductor tower | [`Tower`](../../Geometry/Tower/README.md)
+`conductor` | [-] | Static conductor data | [`Conductor`](../../Geometry/Conductor/README.md)
+$\varepsilon_0$ | [F/m] | Vacuum permittivity | constant
+
+### Parameter Validation
+
+The tower and conductor models must pass their own validation.
+
+### Model Derived Parameters
+
+The tower model provides $h_i$, $D_{ij}$, and $D'_{ij}$. The conductor model
+provides $r_i$.
+
+```math
+\Lambda^{\mathrm{pot}}_{ij} =
+\begin{cases}
+\ln\dfrac{2h_i}{r_i}, & i=j \\
+\ln\dfrac{D'_{ij}}{D_{ij}}, & i\ne j
+\end{cases}
+```
+
+## Model Variables
+
+### Internal Variables
+
+#### Differential
+
+None.
+
+#### Algebraic
+
+Symbol | Units | Description | Note
+------ | ----- | ----------- | ----
+$\mathbf{P}$ | [m/F] | Potential-coefficient matrix | $\mathbb{R}^{K\times K}$
+$\mathbf{G}^{\mathrm{pot}}$ | [S/m] | Potential-derived shunt conductance | zero matrix
+$\mathbf{C}^{\mathrm{pot}}$ | [F/m] | Potential-derived shunt capacitance | $\mathbb{R}^{K\times K}$
+
+### External Variables
+
+#### Differential
+
+None.
+
+#### Algebraic
+
+None.
+
+## Model Equations
+
+### Differential Equations
+
+None.
+
+### Algebraic Equations
+
+```math
+\begin{aligned}
+\mathbf{0} &= -2\pi\varepsilon_0\mathbf{P}
+ + \boldsymbol{\Lambda}^{\mathrm{pot}} \\
+\mathbf{0} &= -\mathbf{G}^{\mathrm{pot}} \\
+\mathbf{0} &= \mathbf{P}\mathbf{C}^{\mathrm{pot}}
+ - \mathbf{I}_{K}
+\end{aligned}
+```
+
+## Initialization
+
+Initialize $\mathbf{P}$ from the log-distance terms, set
+$\mathbf{G}^{\mathrm{pot}}=\mathbf{0}$, and solve
+$\mathbf{P}\mathbf{C}^{\mathrm{pot}}=\mathbf{I}_{K}$.
+
+## Model Outputs
+
+Symbol | Units | Description | Note
+------ | ----- | ----------- | ----
+$\mathbf{G}^{\mathrm{pot}}$ | [S/m] | Potential-derived shunt conductance | zero matrix
+$\mathbf{C}^{\mathrm{pot}}$ | [F/m] | Potential-derived shunt capacitance | $\mathbb{R}^{K\times K}$
diff --git a/GridKit/Model/EMT/Parameters/Effects/SkinEffect/README.md b/GridKit/Model/EMT/Parameters/Effects/SkinEffect/README.md
new file mode 100644
index 000000000..7d4b6b6f9
--- /dev/null
+++ b/GridKit/Model/EMT/Parameters/Effects/SkinEffect/README.md
@@ -0,0 +1,122 @@
+# SkinEffect Model
+
+`SkinEffect` computes frequency-dependent internal resistance and inductance
+vectors for overhead conductors using the simplified skin-effect formulation of
+Monteiro et al. [1].
+
+## Model Parameters
+
+For $K$ physical conductors:
+
+Symbol | Units | JSON | Description | Note
+------ | ----- | ---- | ----------- | ----
+$r_i$ | [m] | `radius` | Outer radius | from [`Conductor`](../../Geometry/Conductor/README.md)
+$\sigma_i$ | [S/m] | `conductivity` | Conductivity | from [`Conductor`](../../Geometry/Conductor/README.md)
+$\mu_i$ | [H/m] | `permeability` | Permeability | from [`Conductor`](../../Geometry/Conductor/README.md)
+
+### Parameter Validation
+
+The connected conductor model owns vector validation. This model requires
+
+```math
+\omega>0 .
+```
+
+The formulation uses the solid cylindrical-conductor approximation in [1].
+
+### Model Derived Parameters
+
+The number of retained root terms is fixed by the model:
+
+```math
+N_s=8 .
+```
+
+For conductor $i$ and retained root $k=1,\dots,N_s$,
+
+```math
+\begin{aligned}
+\xi_k &= \left(k-\frac{1}{4}\right)\pi \\
+R_{ik}^{\mathrm{br}} &=
+ \frac{\xi_k^2}{4\pi\sigma_i r_i^2} \\
+L_i^{\mathrm{br}} &=
+ \frac{\mu_i}{4\pi}
+\end{aligned}
+```
+
+## Model Variables
+
+### Internal Variables
+
+#### Differential
+
+None.
+
+#### Algebraic
+
+Symbol | Units | Description | Note
+------ | ----- | ----------- | ----
+$\mathbf{Q}$ | [$(\Omega/\mathrm{m})^2$] | Branch denominator | $\mathbb{R}^{K\times N_s}$
+$\mathbf{G}$ | [m/$\Omega$] | Real internal-admittance sum | $\mathbb{R}^{K}$
+$\mathbf{H}$ | [s m/$\Omega$] | Inductive internal-admittance sum | $\mathbb{R}^{K}$
+$\mathbf{W}$ | [$(\mathrm{m}/\Omega)^2$] | Internal-impedance denominator | $\mathbb{R}^{K}$
+$\mathbf{r}^{\mathrm{skin}}$ | [$\Omega$/m] | Internal conductor resistance | $\mathbb{R}^{K}$
+$\mathbf{l}^{\mathrm{skin}}$ | [H/m] | Internal conductor inductance | $\mathbb{R}^{K}$
+
+### External Variables
+
+#### Differential
+
+None.
+
+#### Algebraic
+
+None.
+
+## Model Equations
+
+### Differential Equations
+
+None.
+
+### Algebraic Equations
+
+```math
+\begin{aligned}
+0 &= -Q_{ik}
+ + (R_{ik}^{\mathrm{br}})^2
+ + \omega^2(L_i^{\mathrm{br}})^2 \\
+0 &= -G_i
+ + \sum_{k=1}^{N_s}
+ \frac{R_{ik}^{\mathrm{br}}}{Q_{ik}} \\
+0 &= -H_i
+ + \sum_{k=1}^{N_s}
+ \frac{L_i^{\mathrm{br}}}{Q_{ik}} \\
+0 &= -W_i
+ + G_i^2
+ + \omega^2H_i^2 \\
+0 &= -W_i r_i^{\mathrm{skin}}
+ + G_i \\
+0 &= -W_i l_i^{\mathrm{skin}}
+ + H_i
+\end{aligned}
+```
+
+## Initialization
+
+Initialize all algebraic variables from the algebraic equations at the current
+$\omega$.
+
+## Model Outputs
+
+Symbol | Units | Description | Note
+------ | ----- | ----------- | ----
+$\mathbf{r}^{\mathrm{skin}}$ | [$\Omega$/m] | Internal conductor resistance | $\mathbb{R}^{K}$
+$\mathbf{l}^{\mathrm{skin}}$ | [H/m] | Internal conductor inductance | $\mathbb{R}^{K}$
+
+## References
+
+[1] J. H. A. Monteiro, E. C. M. Costa, A. J. G. Pinto, S. Kurokawa,
+O. M. O. Gatous, and J. Pissolato, "Simplified skin-effect formulation
+for power transmission lines," IET Science, Measurement & Technology,
+vol. 8, no. 2, pp. 47-53, 2014. doi:10.1049/iet-smt.2013.0072.
diff --git a/GridKit/Model/EMT/Parameters/Geometry/Conductor/README.md b/GridKit/Model/EMT/Parameters/Geometry/Conductor/README.md
new file mode 100644
index 000000000..74abcc6c0
--- /dev/null
+++ b/GridKit/Model/EMT/Parameters/Geometry/Conductor/README.md
@@ -0,0 +1,91 @@
+# Conductor Model
+
+`Conductor` stores conductor dimensions, material properties, weight, and phase
+labels for the physical conductors in an overhead line.
+
+
+ 
+
+
+## Model Parameters
+
+For $K$ physical conductors:
+
+Symbol | Units | JSON | Description | Note
+------ | ----- | ---- | ----------- | ----
+$r_i$ | [m] | `radius` | Outer radius | $r_i>0$
+$q_i$ | [m] | `inner_radius` | Inner radius | $0\le q_i0$
+$\mu_i$ | [H/m] | `permeability` | Permeability | $\mu_i>0$
+$w_i$ | [N/m] | `weight` | Conductor weight per unit length | $w_i>0$
+$\phi_i$ | [-] | `phase` | Conductor phase label | optional; one of `a`, `b`, `c`, `n`, or `g`
+
+### Parameter Validation
+
+```math
+r_i>q_i\ge0,\qquad
+\sigma_i>0,\qquad
+\mu_i>0,\qquad
+w_i>0,\qquad
+i=1,\dots,K
+```
+
+The conductor vectors use the same conductor order as the other
+conductor-indexed parameter models.
+If supplied, phase labels use the same conductor order. Each phase label
+$\phi_i$ is one of `a`, `b`, `c`, `n`, or `g`, where `g` marks a grounded
+conductor.
+
+### Model Derived Parameters
+
+None.
+
+## Model Variables
+
+`Conductor` is a static data model.
+
+### Internal Variables
+
+#### Differential
+
+None.
+
+#### Algebraic
+
+None.
+
+### External Variables
+
+#### Differential
+
+None.
+
+#### Algebraic
+
+None.
+
+## Model Equations
+
+### Differential Equations
+
+None.
+
+### Algebraic Equations
+
+None.
+
+## Initialization
+
+Validate the conductor dimension, material, weight, and optional phase-label
+vectors.
+
+## Model Outputs
+
+Symbol | Units | Description | Note
+------ | ----- | ----------- | ----
+$\mathbf{r}$ | [m] | Outer-radius vector | $\mathbb{R}^{K}$
+$\mathbf{q}$ | [m] | Inner-radius vector | $\mathbb{R}^{K}$
+$\boldsymbol{\sigma}$ | [S/m] | Conductor conductivity vector | $\mathbb{R}^{K}$
+$\boldsymbol{\mu}$ | [H/m] | Conductor permeability vector | $\mathbb{R}^{K}$
+$\mathbf{w}$ | [N/m] | Conductor weight per-unit-length vector | $\mathbb{R}^{K}$
+$\boldsymbol{\phi}$ | [-] | Phase-label vector | optional; entries in `a`, `b`, `c`, `n`, or `g`
diff --git a/GridKit/Model/EMT/Parameters/Geometry/Path/README.md b/GridKit/Model/EMT/Parameters/Geometry/Path/README.md
new file mode 100644
index 000000000..28df9ed8a
--- /dev/null
+++ b/GridKit/Model/EMT/Parameters/Geometry/Path/README.md
@@ -0,0 +1,122 @@
+# Path Model
+
+`Path` computes the path length $\ell$ used by finite-line response models from
+an explicit length or an ordered GIS route.
+
+
+ 
+
+
+## Model Parameters
+
+For GIS points $n=1,\dots,N_p$:
+
+Symbol | Units | JSON | Description | Note
+------ | ----- | ---- | ----------- | ----
+$\ell^{\mathrm{in}}$ | [m] | `length` | Explicit path length | optional; overrides GIS-derived length
+$\Phi_n$ | [deg] | `path[*].latitude` | Latitude of point $n$ |
+$\Lambda_n$ | [deg] | `path[*].longitude` | Longitude of point $n$ |
+`tower` | [-] | - | Sagged-to-span ratio | from [`Tower`](../Tower/README.md)
+
+The GIS path intervals are not tower spans. GIS points define a long-route
+centerline; `Tower` supplies the sagged-to-span ratio.
+
+### Parameter Validation
+
+When supplied:
+
+```math
+\ell^{\mathrm{in}}>0
+```
+
+When GIS path data is supplied:
+
+```math
+N_p\ge2,\qquad
+-90\le\Phi_n\le90,\qquad
+-180\le\Lambda_n\le180
+```
+
+If `length` is not supplied, the GIS route length and sagged-to-span ratio must
+give $\ell>0$.
+
+### Model Derived Parameters
+
+For fixed mean earth radius
+
+```math
+R_\oplus = 6371008.8\ \mathrm{m}
+```
+
+If `length` is supplied,
+
+```math
+\ell=\ell^{\mathrm{in}}
+```
+
+Otherwise, for GIS intervals $n=1,\dots,N_p-1$:
+
+```math
+\begin{aligned}
+\phi_n &= \frac{\pi}{180}\Phi_n \\
+\lambda_n &= \frac{\pi}{180}\Lambda_n \\
+\Delta\phi_n &= \phi_{n+1}-\phi_n \\
+\Delta\lambda_n &= \lambda_{n+1}-\lambda_n \\
+a_n &= \sin^2\left(\frac{\Delta\phi_n}{2}\right)
+ + \cos\phi_n\cos\phi_{n+1}
+ \sin^2\left(\frac{\Delta\lambda_n}{2}\right) \\
+c_n &= 2\operatorname{atan2}\left(\sqrt{a_n},\sqrt{1-a_n}\right) \\
+s_n &= R_\oplus c_n \\
+S_{\mathrm{path}} &= \sum_{n=1}^{N_p-1} s_n
+\end{aligned}
+```
+
+With sagged-to-span ratio from `Tower`,
+
+```math
+\ell=\rho_{\mathrm{sag}}S_{\mathrm{path}}
+```
+
+## Model Variables
+
+`Path` is a static data model.
+
+### Internal Variables
+
+#### Differential
+
+None.
+
+#### Algebraic
+
+None.
+
+### External Variables
+
+#### Differential
+
+None.
+
+#### Algebraic
+
+None.
+
+## Model Equations
+
+### Differential Equations
+
+None.
+
+### Algebraic Equations
+
+None.
+
+## Initialization
+
+Compute the path length from the explicit length or the GIS route.
+
+## Model Outputs
+
+Symbol | Units | Description | Note
+------ | ----- | ----------- | ----
+$\ell$ | [m] | Path length | scalar
diff --git a/GridKit/Model/EMT/Parameters/Geometry/README.md b/GridKit/Model/EMT/Parameters/Geometry/README.md
new file mode 100644
index 000000000..f6a5c9114
--- /dev/null
+++ b/GridKit/Model/EMT/Parameters/Geometry/README.md
@@ -0,0 +1,33 @@
+# Geometry Models
+
+`Geometry` contains static parameter models that describe the line layout and
+conductor data used by overhead-line calculations.
+
+These models do not own EMT network ports. They provide static inputs or
+derived geometry quantities to the effect and response models.
+
+Model | Description
+----- | -----------
+[`Path`](Path/README.md) | Computes path length for finite-line response models
+[`Tower`](Tower/README.md) | Stores conductor attachment coordinates and span-scale geometry
+[`Conductor`](Conductor/README.md) | Stores conductor dimensions, material properties, weight, and phase labels
+
+## Shared Inputs
+
+Quantity | Description
+-------- | -----------
+`tower.x` | Horizontal conductor attachment coordinates
+`tower.height` | Conductor attachment heights above earth
+`tower.span` | Support-to-support span length
+`tower.tension` | Optional span tension parameter
+`conductors[*].radius` | Outer conductor radius
+`conductors[*].inner_radius` | Inner conductor radius
+`conductors[*].conductivity` | Conductor conductivity
+`conductors[*].permeability` | Conductor permeability
+`conductors[*].weight` | Conductor weight per unit length
+`conductors[*].phase` | Conductor phase label
+`length`, `path` | Explicit length or GIS path data
+
+The number of physical conductors $K$ is inferred from the conductor list.
+Child models own their detailed validation for geometry, material, and path
+inputs.
diff --git a/GridKit/Model/EMT/Parameters/Geometry/Tower/README.md b/GridKit/Model/EMT/Parameters/Geometry/Tower/README.md
new file mode 100644
index 000000000..5be6c9b84
--- /dev/null
+++ b/GridKit/Model/EMT/Parameters/Geometry/Tower/README.md
@@ -0,0 +1,113 @@
+# Tower Model
+
+`Tower` stores conductor attachment coordinates and span-scale geometry.
+
+
+ 
+
+
+## Model Parameters
+
+For physical conductors $i=1,\dots,K$:
+
+Symbol | Units | JSON | Description | Note
+------ | ----- | ---- | ----------- | ----
+`conductor` | [-] | - | Static conductor data | [`Conductor`](../Conductor/README.md)
+$x_i$ | [m] | `tower.x` | Horizontal attachment coordinate | real
+$H_i$ | [m] | `tower.height` | Attachment height above earth | $H_i>0$
+$S$ | [m] | `tower.span` | Support-to-support span length | $S>0$
+$T_i$ | [N] | `tower.tension` | Tension | optional
+
+`Tower` does not own conductor phase labels. Phase labels are conductor
+metadata owned by [`Conductor`](../Conductor/README.md).
+
+
+ 
+
+
+### Parameter Validation
+
+Require finite $x_i$, $H_i>0$, $S>0$, and $D'_{ij}>D_{ij}>0$ for
+$i\ne j$. When tension is supplied, require $T_i>0$, $w_i>0$, and
+$h_i^{\min}>0$.
+
+### Model Derived Parameters
+
+When tension data is supplied,
+
+```math
+\begin{aligned}
+a_i &= \frac{T_i}{w_i} \\
+D_i^\mathrm{sag} &= a_i\left[\cosh\left(\frac{S}{2a_i}\right)-1\right] \\
+\ell_i^{\mathrm{span}} &= 2a_i\sinh\left(\frac{S}{2a_i}\right) \\
+h_i^{\min} &= H_i-D_i^\mathrm{sag} \\
+h_i &= H_i-D_i^\mathrm{sag}
+ + \frac{2a_i^2}{S}\sinh\left(\frac{S}{2a_i}\right)-a_i \\
+d_{ij} &= |x_i-x_j| \\
+D_{ij} &= \sqrt{d_{ij}^2+(h_i-h_j)^2} \\
+D'_{ij} &= \sqrt{d_{ij}^2+(h_i+h_j)^2} \\
+\rho_{\mathrm{sag}} &= \frac{1}{K}\sum_{i=1}^{K}
+ \frac{\ell_i^{\mathrm{span}}}{S}
+\end{aligned}
+```
+
+Here $w_i$ is supplied by `Conductor`. $\rho_{\mathrm{sag}}$ is one
+conductor-averaged scalar.
+
+
+ 
+
+
+## Model Variables
+
+`Tower` is a static data model.
+
+### Internal Variables
+
+#### Differential
+
+None.
+
+#### Algebraic
+
+None.
+
+### External Variables
+
+#### Differential
+
+None.
+
+#### Algebraic
+
+None.
+
+## Model Equations
+
+### Differential Equations
+
+None.
+
+### Algebraic Equations
+
+None.
+
+## Initialization
+
+Compute the span-scale geometry and distance matrices from the tower and
+conductor data.
+
+## Model Outputs
+
+Symbol | Units | Description | Note
+------ | ----- | ----------- | ----
+$x_i$ | [m] | Horizontal attachment coordinate | $\mathbb{R}^{K}$
+$h_i$ | [m] | Conductor height above earth | $\mathbb{R}^{K}$
+$S$ | [m] | Support-to-support span length | scalar
+$d_{ij}$ | [m] | Horizontal separation | $\mathbb{R}^{K\times K}$
+$D_{ij}$ | [m] | Direct conductor distance | $\mathbb{R}^{K\times K}$
+$D'_{ij}$ | [m] | Image-conductor distance | $\mathbb{R}^{K\times K}$
+$D_i^\mathrm{sag}$ | [m] | Midspan sag below attachment height | $\mathbb{R}^{K}$
+$\ell_i^{\mathrm{span}}$ | [m] | Span path length for conductor $i$ | $\mathbb{R}^{K}$
+$h_i^{\min}$ | [m] | Minimum conductor height | $\mathbb{R}^{K}$
+$\rho_{\mathrm{sag}}$ | [-] | Sagged-to-span ratio | scalar
diff --git a/GridKit/Model/EMT/Parameters/README.md b/GridKit/Model/EMT/Parameters/README.md
new file mode 100644
index 000000000..27ba3da46
--- /dev/null
+++ b/GridKit/Model/EMT/Parameters/README.md
@@ -0,0 +1,188 @@
+# EMT Parameters
+
+`Parameters` contains frequency-domain EMT parameter models for overhead-line
+studies. The family READMEs describe the model groups:
+
+Family | Description
+------ | -----------
+[`Geometry`](Geometry/README.md) | Static line geometry, conductor data, span data, and path length
+[`Effects`](Effects/README.md) | Physical effects used to assemble per-unit-length series and shunt quantities
+[`Response`](Response/README.md) | Propagation, finite-length response, and characteristic quantities derived from the assembled parameters
+
+## Overhead Aggregate
+
+`Overhead` aggregates the implemented overhead-line parameter models for one
+angular frequency. It owns global state layout, submodel wiring, and monitor
+selection for frequency sweeps.
+
+`Overhead` is not an EMT network component and does not own bus ports. Sweep
+endpoints, sampling, and linear or logarithmic grids belong to the application
+or study driver.
+
+### Model Parameters
+
+Symbol | Units | JSON | Description | Note
+------ | ----- | ---- | ----------- | ----
+`path` | [-] | `length`, `path` | Path definition used to compute line length | passed to [`Path`](Geometry/Path/README.md)
+`tower` | [-] | `tower.x`, `tower.height`, `tower.span`, `tower.tension` | Tower attachment and span geometry | passed to [`Tower`](Geometry/Tower/README.md)
+`conductor` | [-] | `conductors[*].radius`, `conductors[*].inner_radius`, `conductors[*].conductivity`, `conductors[*].permeability`, `conductors[*].weight`, `conductors[*].phase` | Conductor dimensions, material, weight, and phase data | passed to [`Conductor`](Geometry/Conductor/README.md)
+$\sigma_g$ | [S/m] | `earth_conductivity` | Earth conductivity | passed to [`Carson`](Effects/Carson/README.md)
+$\varepsilon_g$ | [F/m] | `earth_permittivity` | Earth permittivity | passed to [`Carson`](Effects/Carson/README.md)
+
+#### Parameter Validation
+
+The aggregate parser rejects invalid line-data fields before constructing the
+child models. Detailed validation belongs to the child models.
+
+#### Model Derived Parameters
+
+None. The aggregate constructs and wires submodels from the parsed line data.
+
+### Model Submodels
+
+Submodel | Inputs | Outputs
+-------- | ------ | -------
+[`Conductor`](Geometry/Conductor/README.md) | `conductor` | $r_i$, $q_i$, $\sigma_i$, $\mu_i$, $w_i$, $\phi_i$
+[`Tower`](Geometry/Tower/README.md) | `tower`, `conductor` | $x_i$, $h_i$, $S$, $d_{ij}$, $D_{ij}$, $D'_{ij}$, $\ell_i^{\mathrm{span}}$, $\rho_{\mathrm{sag}}$
+[`Path`](Geometry/Path/README.md) | `length`, `path`, `Tower` | $\ell$
+[`GeometricInductance`](Effects/GeometricInductance/README.md) | `tower`, `conductor` | $\mathbf{L}^{\mathrm{geo}}$
+[`SkinEffect`](Effects/SkinEffect/README.md) | `conductor` | $\mathbf{r}^{\mathrm{skin}}$, $\mathbf{l}^{\mathrm{skin}}$
+[`Carson`](Effects/Carson/README.md) | `tower`, $\sigma_g$, $\varepsilon_g$ | $\mathbf{R}^{\mathrm{carson}}$, $\mathbf{L}^{\mathrm{carson}}$
+[`SeriesImpedance`](Effects/SeriesImpedance/README.md) | `SkinEffect`, `GeometricInductance`, `Carson` | $\mathbf{R}'$, $\mathbf{L}'$
+[`ShuntPotential`](Effects/ShuntPotential/README.md) | `tower`, `conductor` | $\mathbf{G}^{\mathrm{pot}}$, $\mathbf{C}^{\mathrm{pot}}$
+[`ShuntAdmittance`](Effects/ShuntAdmittance/README.md) | `ShuntPotential` | $\mathbf{G}'$, $\mathbf{C}'$
+[`Gamma`](Response/Gamma/README.md) | `SeriesImpedance`, `ShuntAdmittance` | $\boldsymbol{\Gamma}$, $\mathbf{T}_v$, $\mathbf{T}_i$, $\mathbf{a}$, $\mathbf{b}$
+[`Tau`](Response/Tau/README.md) | `Gamma`, `Path` | $\boldsymbol{\tau}$
+[`H`](Response/H/README.md) | `Gamma`, `Path` | $\mathbf{H}$
+[`Yc`](Response/Yc/README.md) | `SeriesImpedance`, `ShuntAdmittance` | $\mathbf{Y}_c$
+[`Zc`](Response/Zc/README.md) | `SeriesImpedance`, `ShuntAdmittance` | $\mathbf{Z}_c$
+
+### Signal Wiring
+
+A typical sweep wires static line data into geometry and effect models, assembles
+per-unit-length quantities, and then evaluates response models. Arrows point
+from the producer to the consumer.
+
+```mermaid
+flowchart LR
+ path[Path]
+ tower[Tower]
+
+ subgraph effects["Effect models"]
+ direction TB
+ geo[GeometricInductance]
+ skin[SkinEffect]
+ carson[Carson]
+ shuntpot[ShuntPotential]
+ end
+
+ subgraph assembled["Assembled parameters"]
+ direction TB
+ series[SeriesImpedance]
+ shuntadm[ShuntAdmittance]
+ end
+
+ subgraph response["Response"]
+ direction TB
+ tau[Tau]
+ h[H]
+ gamma[Gamma]
+ yc[Yc]
+ zc[Zc]
+ end
+
+ path --> tau
+ path --> h
+
+ tower --> path
+
+ tower --> geo
+ tower --> carson
+ tower --> shuntpot
+
+ geo --> series
+ skin --> series
+ carson --> series
+ shuntpot --> shuntadm
+
+ series --> gamma
+ shuntadm --> gamma
+ series --> yc
+ shuntadm --> yc
+ series --> zc
+ shuntadm --> zc
+
+ gamma --> tau
+ gamma --> h
+
+ classDef geometry fill:#edf3e6,stroke:#78915c,stroke-width:1.2px,color:#243315;
+ classDef effect fill:#f5ecd9,stroke:#9a7b43,stroke-width:1.2px,color:#3b2b11;
+ classDef assembled fill:#e4f1df,stroke:#698b5e,stroke-width:1.2px,color:#1f3319;
+ classDef derived fill:#efe8f6,stroke:#77608f,stroke-width:1.2px,color:#2d2038;
+ class tower,path geometry;
+ class geo,skin,carson,shuntpot effect;
+ class series,shuntadm assembled;
+ class gamma,tau,h,yc,zc derived;
+```
+
+#### Directional Wiring Table
+
+Stage | Source | Target | Values
+----- | ------ | ------ | ------
+Geometry data | `tower` | [`GeometricInductance`](Effects/GeometricInductance/README.md) | $h_i$, $D_{ij}$, $D'_{ij}$
+Geometry data | `conductor` | [`GeometricInductance`](Effects/GeometricInductance/README.md) | $r_i$
+Geometry data | `tower` | [`Carson`](Effects/Carson/README.md) | $h_i$, $h_j$, $d_{ij}$
+Geometry data | `tower` | [`ShuntPotential`](Effects/ShuntPotential/README.md) | $h_i$, $D_{ij}$, $D'_{ij}$
+Geometry data | `conductor` | [`ShuntPotential`](Effects/ShuntPotential/README.md) | $r_i$
+Material data | `conductor` | [`SkinEffect`](Effects/SkinEffect/README.md) | $r_i$, $\sigma_i$, $\mu_i$
+Earth material | `earth_conductivity`, `earth_permittivity` | [`Carson`](Effects/Carson/README.md) | $\sigma_g$, $\varepsilon_g$
+Span geometry | `tower`, `conductor` | [`Tower`](Geometry/Tower/README.md) | $S$, $\ell_i^{\mathrm{span}}$, $\rho_{\mathrm{sag}}$
+Series assembly | [`SkinEffect`](Effects/SkinEffect/README.md) | [`SeriesImpedance`](Effects/SeriesImpedance/README.md) | $\mathbf{r}^{\mathrm{skin}}$, $\mathbf{l}^{\mathrm{skin}}$
+Series assembly | [`GeometricInductance`](Effects/GeometricInductance/README.md) | [`SeriesImpedance`](Effects/SeriesImpedance/README.md) | $\mathbf{L}^{\mathrm{geo}}$
+Series assembly | [`Carson`](Effects/Carson/README.md) | [`SeriesImpedance`](Effects/SeriesImpedance/README.md) | $\mathbf{R}^{\mathrm{carson}}$, $\mathbf{L}^{\mathrm{carson}}$
+Shunt assembly | [`ShuntPotential`](Effects/ShuntPotential/README.md) | [`ShuntAdmittance`](Effects/ShuntAdmittance/README.md) | $\mathbf{G}^{\mathrm{pot}}$, $\mathbf{C}^{\mathrm{pot}}$
+Response inputs | [`SeriesImpedance`](Effects/SeriesImpedance/README.md) | [`Gamma`](Response/Gamma/README.md), [`Yc`](Response/Yc/README.md), [`Zc`](Response/Zc/README.md) | $\mathbf{R}'$, $\mathbf{L}'$
+Response inputs | [`ShuntAdmittance`](Effects/ShuntAdmittance/README.md) | [`Gamma`](Response/Gamma/README.md), [`Yc`](Response/Yc/README.md), [`Zc`](Response/Zc/README.md) | $\mathbf{G}'$, $\mathbf{C}'$
+Finite-line inputs | `length`, `path`, [`Tower`](Geometry/Tower/README.md) | [`Path`](Geometry/Path/README.md) | $\ell$
+Finite-line response | [`Gamma`](Response/Gamma/README.md) | [`Tau`](Response/Tau/README.md) | $\mathbf{b}$
+Finite-line response | [`Path`](Geometry/Path/README.md) | [`Tau`](Response/Tau/README.md) | $\ell$
+Finite-line response | [`Gamma`](Response/Gamma/README.md) | [`H`](Response/H/README.md) | $\mathbf{a}$, $\mathbf{b}$, $\dot{\mathbf{a}}$, $\dot{\mathbf{b}}$
+Finite-line response | [`Path`](Geometry/Path/README.md) | [`H`](Response/H/README.md) | $\ell$
+
+### Model Variables
+
+The aggregate stores one concatenated state vector across the submodels listed
+above. Each child README documents the variables and residuals owned by that
+child model.
+
+### Model Equations
+
+`Overhead` owns no additional residual equations. It binds the child models into
+one evaluator and calls each child residual and Jacobian.
+
+### Initialization
+
+Construct the child models from the parsed line data, bind their states into the
+aggregate vector, initialize each child model at the current $\omega$, and start
+the configured monitor sinks.
+
+### Model Outputs
+
+Model outputs are the child-model outputs listed in the submodel table.
+
+### Monitors
+
+Monitor | Symbol | Units | Shape | Description
+------- | ------ | ----- | ----- | -----------
+`R` | $\mathbf{R}'$ | [$\Omega$/m] | $K\times K$ | Series resistance
+`L` | $\mathbf{L}'$ | [H/m] | $K\times K$ | Series inductance
+`G` | $\mathbf{G}'$ | [S/m] | $K\times K$ | Shunt conductance
+`C` | $\mathbf{C}'$ | [F/m] | $K\times K$ | Shunt capacitance
+`Tv` | $\mathbf{T}_v$ | [-] | $K\times K$ | Voltage modal transformation matrix
+`Ti` | $\mathbf{T}_i$ | [-] | $K\times K$ | Current modal transformation matrix
+`Alpha` | $\mathbf{a}$ | [1/m] | $K$ | Modal attenuation constants
+`Beta` | $\mathbf{b}$ | [1/m] | $K$ | Modal phase constants
+`Tau` | $\boldsymbol{\tau}$ | [s] | $K$ | Modal phase delay
+`H` | $\mathbf{H}$ | [-] | $K$ | Modal finite-length propagation function
+`Yc` | $\mathbf{Y}_c=\mathbf{G}_c+j\mathbf{B}_c$ | [S] | $K\times K$ | Characteristic admittance
+`Zc` | $\mathbf{Z}_c=\mathbf{R}_c+j\mathbf{X}_c$ | [$\Omega$] | $K\times K$ | Characteristic impedance
diff --git a/GridKit/Model/EMT/Parameters/Response/Gamma/README.md b/GridKit/Model/EMT/Parameters/Response/Gamma/README.md
new file mode 100644
index 000000000..282ce4ffb
--- /dev/null
+++ b/GridKit/Model/EMT/Parameters/Response/Gamma/README.md
@@ -0,0 +1,228 @@
+# Gamma Model
+
+`Gamma` computes the full-conductor propagation constant matrix and tracks its
+modal propagation constants.
+
+Notes:
+- This model uses the V-definition: the series matrix pair is on the left of
+ the shunt matrix pair.
+- The real and imaginary parts of $\boldsymbol{\Gamma}$ are
+ $\boldsymbol{\alpha}$ and $\boldsymbol{\beta}$.
+- Eigenvalue computation is not expressed as a DAE, so modal branches are
+ initialized from $\boldsymbol{\Gamma}^2$ at one value of $\omega$ and tracked
+ as $\omega$ changes.
+- The modal tracking equations assume each tracked modal branch is simple.
+
+The propagation constant is decomposed as
+$\boldsymbol{\Gamma}=\boldsymbol{\alpha}+j\boldsymbol{\beta}$.
+
+The complex form typically given for this convention is:
+
+```math
+\boldsymbol{\Gamma} =
+\sqrt{
+(\mathbf{R}' + j\mathbf{X}')
+(\mathbf{G}' + j\mathbf{B}')
+}
+```
+
+Equivalently,
+
+```math
+\boldsymbol{\Gamma}^2 =
+(\mathbf{R}' + j\mathbf{X}')
+(\mathbf{G}' + j\mathbf{B}')
+```
+
+## Model Parameters
+
+None. `Gamma` combines full-conductor parameter outputs for $K$ physical
+conductors.
+
+### Parameter Validation
+
+The full-conductor inputs must be square and have the same dimension.
+
+### Model Derived Parameters
+
+None.
+
+## Model Variables
+
+### Internal Variables
+
+#### Differential
+
+A dot denotes derivative with respect to $\omega$.
+
+Symbol | Units | Description | Note
+------ | ----- | ----------- | ----
+$\boldsymbol{\alpha}$ | [1/m] | Attenuation constant matrix | $\mathbb{R}^{K\times K}$
+$\boldsymbol{\beta}$ | [1/m] | Phase constant matrix | $\mathbb{R}^{K\times K}$
+$a_m$ | [1/m] | Modal attenuation constant for mode $m$ | real
+$b_m$ | [1/m] | Modal phase constant for mode $m$ | real
+$\mathbf{t}^{\mathrm r}_{v,m}$ | [-] | Real part of voltage modal transformation vector | $\mathbf{t}^{\mathrm r}_{v,m}\in\mathbb{R}^K$
+$\mathbf{t}^{\mathrm i}_{v,m}$ | [-] | Imaginary part of voltage modal transformation vector | $\mathbf{t}^{\mathrm i}_{v,m}\in\mathbb{R}^K$
+$\mathbf{t}^{\mathrm r}_{i,m}$ | [-] | Real part of current modal transformation vector | $\mathbf{t}^{\mathrm r}_{i,m}\in\mathbb{R}^K$
+$\mathbf{t}^{\mathrm i}_{i,m}$ | [-] | Imaginary part of current modal transformation vector | $\mathbf{t}^{\mathrm i}_{i,m}\in\mathbb{R}^K$
+
+#### Algebraic
+
+None.
+
+### External Variables
+
+#### Differential
+
+None.
+
+#### Algebraic
+
+Symbol | Units | Description | Note
+------ | ----- | ----------- | ----
+$\mathbf{R}'$ | [$\Omega$/m] | Full-conductor resistance | from [`SeriesImpedance`](../../Effects/SeriesImpedance/README.md)
+$\mathbf{X}'$ | [$\Omega$/m] | Full-conductor reactance | $\omega\mathbf{L}'$ from [`SeriesImpedance`](../../Effects/SeriesImpedance/README.md)
+$\mathbf{G}'$ | [S/m] | Full-conductor shunt conductance | from [`ShuntAdmittance`](../../Effects/ShuntAdmittance/README.md)
+$\mathbf{B}'$ | [S/m] | Full-conductor shunt susceptance | $\omega\mathbf{C}'$ from [`ShuntAdmittance`](../../Effects/ShuntAdmittance/README.md)
+
+## Model Equations
+
+### Differential Equations
+
+For each mode $m=1,\dots,K$:
+
+```math
+\begin{aligned}
+\mathbf{0} &=
+ \dot{\boldsymbol{\alpha}}\mathbf{t}^{\mathrm r}_{v,m}
+ - \dot{\boldsymbol{\beta}}\mathbf{t}^{\mathrm i}_{v,m}
+ + \left(\boldsymbol{\alpha}-a_m\mathbf{I}\right)\dot{\mathbf{t}}^{\mathrm r}_{v,m}
+ - \left(\boldsymbol{\beta}-b_m\mathbf{I}\right)\dot{\mathbf{t}}^{\mathrm i}_{v,m}
+ - \dot{a}_m\mathbf{t}^{\mathrm r}_{v,m}
+ + \dot{b}_m\mathbf{t}^{\mathrm i}_{v,m} \\
+\mathbf{0} &=
+ \dot{\boldsymbol{\alpha}}\mathbf{t}^{\mathrm i}_{v,m}
+ + \dot{\boldsymbol{\beta}}\mathbf{t}^{\mathrm r}_{v,m}
+ + \left(\boldsymbol{\beta}-b_m\mathbf{I}\right)\dot{\mathbf{t}}^{\mathrm r}_{v,m}
+ + \left(\boldsymbol{\alpha}-a_m\mathbf{I}\right)\dot{\mathbf{t}}^{\mathrm i}_{v,m}
+ - \dot{a}_m\mathbf{t}^{\mathrm i}_{v,m}
+ - \dot{b}_m\mathbf{t}^{\mathrm r}_{v,m} \\
+\mathbf{0} &=
+ \dot{\boldsymbol{\alpha}}^{\mathsf{T}}\mathbf{t}^{\mathrm r}_{i,m}
+ + \dot{\boldsymbol{\beta}}^{\mathsf{T}}\mathbf{t}^{\mathrm i}_{i,m}
+ + \left(\boldsymbol{\alpha}^{\mathsf{T}}-a_m\mathbf{I}\right)\dot{\mathbf{t}}^{\mathrm r}_{i,m}
+ + \left(\boldsymbol{\beta}^{\mathsf{T}}-b_m\mathbf{I}\right)\dot{\mathbf{t}}^{\mathrm i}_{i,m}
+ - \dot{a}_m\mathbf{t}^{\mathrm r}_{i,m}
+ - \dot{b}_m\mathbf{t}^{\mathrm i}_{i,m} \\
+\mathbf{0} &=
+ \dot{\boldsymbol{\alpha}}^{\mathsf{T}}\mathbf{t}^{\mathrm i}_{i,m}
+ - \dot{\boldsymbol{\beta}}^{\mathsf{T}}\mathbf{t}^{\mathrm r}_{i,m}
+ - \left(\boldsymbol{\beta}^{\mathsf{T}}-b_m\mathbf{I}\right)\dot{\mathbf{t}}^{\mathrm r}_{i,m}
+ + \left(\boldsymbol{\alpha}^{\mathsf{T}}-a_m\mathbf{I}\right)\dot{\mathbf{t}}^{\mathrm i}_{i,m}
+ - \dot{a}_m\mathbf{t}^{\mathrm i}_{i,m}
+ + \dot{b}_m\mathbf{t}^{\mathrm r}_{i,m}
+\end{aligned}
+```
+
+### Algebraic Equations
+
+```math
+\begin{aligned}
+\mathbf{0} &= -\mathbf{R}'\mathbf{G}'
+ + \mathbf{X}'\mathbf{B}'
+ + \boldsymbol{\alpha}\boldsymbol{\alpha}
+ - \boldsymbol{\beta}\boldsymbol{\beta} \\
+\mathbf{0} &= -\mathbf{R}'\mathbf{B}'
+ - \mathbf{X}'\mathbf{G}'
+ + \boldsymbol{\alpha}\boldsymbol{\beta}
+ + \boldsymbol{\beta}\boldsymbol{\alpha} \\
+0 &= \left(\mathbf{t}^{\mathrm r}_{i,m}\right)^{\mathsf{T}}\mathbf{t}^{\mathrm r}_{v,m}
+ + \left(\mathbf{t}^{\mathrm i}_{i,m}\right)^{\mathsf{T}}\mathbf{t}^{\mathrm i}_{v,m}
+ - 1 \\
+0 &= \left(\mathbf{t}^{\mathrm r}_{i,m}\right)^{\mathsf{T}}\mathbf{t}^{\mathrm i}_{v,m}
+ - \left(\mathbf{t}^{\mathrm i}_{i,m}\right)^{\mathsf{T}}\mathbf{t}^{\mathrm r}_{v,m}
+\end{aligned}
+```
+
+## Initialization
+
+At the initial frequency, compute the eigenvalues and right eigenvectors of
+$\boldsymbol{\Gamma}^2$:
+
+```math
+\boldsymbol{\Gamma}^2\mathbf{t}_m
+ = \mu_m\mathbf{t}_m
+```
+
+Then initialize
+$\lambda_m=\sqrt{\mu_m}=a_m+jb_m$ and construct
+$\boldsymbol{\Gamma}$ with the same eigenvectors:
+
+```math
+\begin{aligned}
+\boldsymbol{\Gamma}\mathbf{t}_m
+ &= \lambda_m\mathbf{t}_m,\qquad
+\mathbf{l}_m^*\mathbf{t}_m=1
+\end{aligned}
+```
+
+Use $\lambda_m=a_m+jb_m$,
+$\mathbf{t}_m=\mathbf{t}^{\mathrm r}_{v,m}+j\mathbf{t}^{\mathrm i}_{v,m}$, and
+$\mathbf{l}_m=\mathbf{t}^{\mathrm r}_{i,m}+j\mathbf{t}^{\mathrm i}_{i,m}$.
+
+## Monitors
+
+Monitor | Symbol | Units | Shape | Description
+------- | ------ | ----- | ----- | -----------
+`Tv` | $\mathbf{T}_v$ | [-] | $K\times K$ | Voltage modal transformation matrix
+`Ti` | $\mathbf{T}_i$ | [-] | $K\times K$ | Current modal transformation matrix
+`Alpha` | $\mathbf{a}$ | [1/m] | $K$ | Modal attenuation constants
+`Beta` | $\mathbf{b}$ | [1/m] | $K$ | Modal phase constants
+
+The monitored transformation matrices use
+
+```math
+\mathbf{T}_v =
+\mathbf{T}^{\mathrm r}_v+j\mathbf{T}^{\mathrm i}_v,\qquad
+\mathbf{T}_i =
+\mathbf{T}^{\mathrm r}_i+j\mathbf{T}^{\mathrm i}_i,\qquad
+\mathbf{T}_i^{\mathsf H}\mathbf{T}_v=\mathbf{I}.
+```
+
+Both $\mathbf{T}_v$ and $\mathbf{T}_i$ are reported as $K\times K$
+conductor-by-mode matrices. Column $m$ matches the ordering of `Alpha_m` and
+`Beta_m`.
+
+The voltage and current modal transforms are dual:
+
+```math
+\mathbf{v}=\mathbf{T}_v\hat{\mathbf{v}},\qquad
+\hat{\mathbf{v}}=\mathbf{T}_i^{\mathsf H}\mathbf{v}
+```
+
+```math
+\mathbf{i}=\mathbf{T}_i\hat{\mathbf{i}},\qquad
+\hat{\mathbf{i}}=\mathbf{T}_v^{\mathsf H}\mathbf{i}.
+```
+
+GridKit uses the current-form propagation matrix because `LineDistributed`
+propagates reflected current to incident current:
+
+```math
+\mathbf{H}^{\mathrm{mps}}_i(s)
+=
+\mathbf{T}_i(s)\widehat{\mathbf{H}}^{\mathrm{mps}}(s)
+\mathbf{T}_v(s)^{\mathsf H}.
+```
+
+The dual voltage-form propagation matrix is
+
+```math
+\mathbf{H}^{\mathrm{mps}}_v(s)
+=
+\mathbf{T}_v(s)\widehat{\mathbf{H}}^{\mathrm{mps}}(s)
+\mathbf{T}_i(s)^{\mathsf H}.
+```
+
+The phase-domain matrices $\boldsymbol{\alpha}$ and $\boldsymbol{\beta}$ are
+internal `Gamma` states and are not monitors.
diff --git a/GridKit/Model/EMT/Parameters/Response/H/README.md b/GridKit/Model/EMT/Parameters/Response/H/README.md
new file mode 100644
index 000000000..a03138264
--- /dev/null
+++ b/GridKit/Model/EMT/Parameters/Response/H/README.md
@@ -0,0 +1,134 @@
+# H Model
+
+`H` computes the modal-domain finite-length propagation function from modal
+propagation constants.
+
+The model is real-valued in implementation. The real and imaginary parts of
+$h_m$ are owned as separate differential states.
+
+`H` uses derivative signals from `Gamma`. In logarithmic frequency sweeps,
+`LogEvaluator` converts solver derivatives to derivatives with respect to
+angular frequency before `H` is evaluated.
+
+```math
+h_m = \exp(-\gamma_m \ell),\qquad
+\gamma_m = a_m + j b_m
+```
+
+Equivalently,
+
+```math
+\begin{aligned}
+h^{\mathrm r}_m &=
+e^{-a_m\ell}\cos(b_m\ell) \\
+h^{\mathrm i}_m &=
+-e^{-a_m\ell}\sin(b_m\ell)
+\end{aligned}
+```
+
+The differential form used during the sweep is
+
+```math
+\dot h_m = -\ell \dot\gamma_m h_m,\qquad
+\dot\gamma_m = \dot a_m + j\dot b_m .
+```
+
+## Model Parameters
+
+Symbol | Units | Description | Note
+------ | ----- | ----------- | ----
+$\ell$ | [m] | Path length | from [`Path`](../../Geometry/Path/README.md)
+
+### Parameter Validation
+
+The path length must satisfy
+
+```math
+\ell > 0 .
+```
+
+The connected `Gamma` model owns modal-vector validation.
+
+### Model Derived Parameters
+
+None.
+
+## Model Variables
+
+### Internal Variables
+
+#### Differential
+
+Symbol | Units | Description | Note
+------ | ----- | ----------- | ----
+$h^{\mathrm r}_m$ | [-] | Real part of modal propagation function for mode $m$ | real
+$h^{\mathrm i}_m$ | [-] | Imaginary part of modal propagation function for mode $m$ | real
+
+#### Algebraic
+
+None.
+
+### External Variables
+
+#### Differential
+
+Symbol | Units | Description | Note
+------ | ----- | ----------- | ----
+$\dot a_m$ | [s/m] | Modal attenuation derivative for mode $m$ | from [`Gamma`](../Gamma/README.md)
+$\dot b_m$ | [s/m] | Modal phase derivative for mode $m$ | from [`Gamma`](../Gamma/README.md)
+
+#### Algebraic
+
+Symbol | Units | Description | Note
+------ | ----- | ----------- | ----
+$a_m$ | [1/m] | Modal attenuation constant for mode $m$ | from [`Gamma`](../Gamma/README.md)
+$b_m$ | [1/m] | Modal phase constant for mode $m$ | from [`Gamma`](../Gamma/README.md)
+
+## Model Equations
+
+### Differential Equations
+
+For each mode $m=1,\dots,K$:
+
+```math
+\begin{aligned}
+0 &= -\dot h^{\mathrm r}_m
+ - \ell\left(\dot a_m h^{\mathrm r}_m
+ - \dot b_m h^{\mathrm i}_m\right) \\
+0 &= -\dot h^{\mathrm i}_m
+ - \ell\left(\dot a_m h^{\mathrm i}_m
+ + \dot b_m h^{\mathrm r}_m\right)
+\end{aligned}
+```
+
+### Algebraic Equations
+
+None.
+
+## Initialization
+
+Initialize $h^{\mathrm r}_m$ and $h^{\mathrm i}_m$ from the current $a_m$ and
+$b_m$ inputs using the closed-form expression above. Initialize the derivatives
+from $\dot h_m=-\ell\dot\gamma_m h_m$.
+
+## Model Outputs
+
+Symbol | Units | Description | Note
+------ | ----- | ----------- | ----
+$\mathbf{h}^{\mathrm r}$ | [-] | Real part of modal propagation function | $\mathbb{R}^K$
+$\mathbf{h}^{\mathrm i}$ | [-] | Imaginary part of modal propagation function | $\mathbb{R}^K$
+
+## Monitors
+
+Monitor | Symbol | Units | Shape | Description
+------- | ------ | ----- | ----- | -----------
+`H` | $\mathbf{h}^{\mathrm r}+j\mathbf{h}^{\mathrm i}$ | [-] | $K$ | Modal propagation function
+
+CSV output uses explicit real and imaginary columns:
+
+```text
+Overhead_H_real_m
+Overhead_H_imag_m
+```
+
+No complex-valued states, residuals, monitor storage, or model API are used.
diff --git a/GridKit/Model/EMT/Parameters/Response/README.md b/GridKit/Model/EMT/Parameters/Response/README.md
new file mode 100644
index 000000000..a4ae4c0f1
--- /dev/null
+++ b/GridKit/Model/EMT/Parameters/Response/README.md
@@ -0,0 +1,36 @@
+# Response Models
+
+`Response` contains the propagation and characteristic models derived from
+assembled full-conductor overhead-line parameters.
+
+These models consume the per-unit-length matrices from
+[`SeriesImpedance`](../Effects/SeriesImpedance/README.md) and
+[`ShuntAdmittance`](../Effects/ShuntAdmittance/README.md). Finite-line response
+models also consume the path length from [`Path`](../Geometry/Path/README.md).
+They are evaluated at the current system parameter $\omega$.
+
+Model | Description
+----- | -----------
+[`Gamma`](Gamma/README.md) | Computes propagation constant matrices and modal propagation constants
+[`Tau`](Tau/README.md) | Computes finite-length modal phase delay
+[`H`](H/README.md) | Computes modal finite-length propagation function
+[`Yc`](Yc/README.md) | Computes characteristic admittance
+[`Zc`](Zc/README.md) | Computes characteristic impedance
+
+## Inputs
+
+Quantity | Source | Used By
+-------- | ------ | -------
+$\mathbf{R}'$, $\mathbf{L}'$ | [`SeriesImpedance`](../Effects/SeriesImpedance/README.md) | `Gamma`, `Yc`, `Zc`
+$\mathbf{G}'$, $\mathbf{C}'$ | [`ShuntAdmittance`](../Effects/ShuntAdmittance/README.md) | `Gamma`, `Yc`, `Zc`
+$\ell$ | [`Path`](../Geometry/Path/README.md) | `Tau`, `H`
+
+## Outputs
+
+Quantity | Produced By
+-------- | -----------
+$\boldsymbol{\Gamma}$, $\mathbf{T}_v$, $\mathbf{T}_i$, $\mathbf{a}$, $\mathbf{b}$ | [`Gamma`](Gamma/README.md)
+$\boldsymbol{\tau}$ | [`Tau`](Tau/README.md)
+$\mathbf{H}$ | [`H`](H/README.md)
+$\mathbf{Y}_c$ | [`Yc`](Yc/README.md)
+$\mathbf{Z}_c$ | [`Zc`](Zc/README.md)
diff --git a/GridKit/Model/EMT/Parameters/Response/Tau/README.md b/GridKit/Model/EMT/Parameters/Response/Tau/README.md
new file mode 100644
index 000000000..608f502e9
--- /dev/null
+++ b/GridKit/Model/EMT/Parameters/Response/Tau/README.md
@@ -0,0 +1,74 @@
+# Tau Model
+
+`Tau` computes modal phase delay for a finite line length from modal
+phase constants.
+
+## Model Parameters
+
+Symbol | Units | Description | Note
+------ | ----- | ----------- | ----
+$\ell$ | [m] | Path length | from [`Path`](../../Geometry/Path/README.md)
+
+### Parameter Validation
+
+The connected `Gamma` model owns modal-vector validation. This model requires the
+path length and current sweep point to satisfy
+
+```math
+\ell > 0,\qquad \omega > 0 .
+```
+
+### Model Derived Parameters
+
+None.
+
+## Model Variables
+
+### Internal Variables
+
+#### Differential
+
+None.
+
+#### Algebraic
+
+Symbol | Units | Description | Note
+------ | ----- | ----------- | ----
+$\tau_m$ | [s] | Modal phase delay for mode $m$ | real
+
+### External Variables
+
+#### Differential
+
+None.
+
+#### Algebraic
+
+Symbol | Units | Description | Note
+------ | ----- | ----------- | ----
+$b_m$ | [1/m] | Modal phase constant for mode $m$ | from [`Gamma`](../Gamma/README.md)
+
+## Model Equations
+
+### Differential Equations
+
+None.
+
+### Algebraic Equations
+
+For each mode $m=1,\dots,K$:
+
+```math
+0 = -\tau_m + \frac{\ell b_m}{\omega}
+```
+
+## Initialization
+
+Initialize $\tau_m$ from $\ell$, the current $\omega$, and the current $b_m$
+inputs.
+
+## Model Outputs
+
+Symbol | Units | Description | Note
+------ | ----- | ----------- | ----
+$\boldsymbol{\tau}$ | [s] | Modal phase delay | $\boldsymbol{\tau}\in\mathbb{R}^K$
diff --git a/GridKit/Model/EMT/Parameters/Response/Yc/README.md b/GridKit/Model/EMT/Parameters/Response/Yc/README.md
new file mode 100644
index 000000000..ff235c839
--- /dev/null
+++ b/GridKit/Model/EMT/Parameters/Response/Yc/README.md
@@ -0,0 +1,105 @@
+# Yc Model
+
+`Yc` computes the full-conductor characteristic admittance from the
+per-unit-length series impedance and shunt admittance matrices.
+
+Notes:
+- For multiconductor lines, the V-definition and I-definition differ by the
+ ordering of the matrix products.
+- This model uses the V-definition: the series matrix pair multiplies
+ $\mathbf{Y}_c^2$ on the left.
+- The I-definition places the series matrix pair on the right.
+- The real and imaginary parts of $\mathbf{Y}_c$ are $\mathbf{G}_c$ and
+ $\mathbf{B}_c$.
+
+The characteristic admittance is decomposed as
+$\mathbf{Y}_c=\mathbf{G}_c+j\mathbf{B}_c$.
+
+The complex form typically given for this convention is:
+
+```math
+\mathbf{Y}_c =
+\sqrt{
+(\mathbf{R}' + j\mathbf{X}')^{-1}
+(\mathbf{G}' + j\mathbf{B}')
+}
+```
+
+## Model Parameters
+
+None. `Yc` combines full-conductor parameter outputs for $K$ physical
+conductors.
+
+### Parameter Validation
+
+The full-conductor inputs must be square and have the same dimension.
+
+### Model Derived Parameters
+
+None.
+
+## Model Variables
+
+### Internal Variables
+
+#### Differential
+
+None.
+
+#### Algebraic
+
+Symbol | Units | Description | Note
+------ | ----- | ----------- | ----
+$\mathbf{G}_c$ | [S] | Characteristic conductance | $\mathbb{R}^{K\times K}$
+$\mathbf{B}_c$ | [S] | Characteristic susceptance | $\mathbb{R}^{K\times K}$
+
+### External Variables
+
+#### Differential
+
+None.
+
+#### Algebraic
+
+Symbol | Units | Description | Note
+------ | ----- | ----------- | ----
+$\mathbf{R}'$ | [$\Omega$/m] | Full-conductor resistance | from [`SeriesImpedance`](../../Effects/SeriesImpedance/README.md)
+$\mathbf{X}'$ | [$\Omega$/m] | Full-conductor reactance | $\omega\mathbf{L}'$ from [`SeriesImpedance`](../../Effects/SeriesImpedance/README.md)
+$\mathbf{G}'$ | [S/m] | Full-conductor shunt conductance | from [`ShuntAdmittance`](../../Effects/ShuntAdmittance/README.md)
+$\mathbf{B}'$ | [S/m] | Full-conductor shunt susceptance | $\omega\mathbf{C}'$ from [`ShuntAdmittance`](../../Effects/ShuntAdmittance/README.md)
+
+## Model Equations
+
+### Differential Equations
+
+None.
+
+### Algebraic Equations
+
+```math
+\begin{aligned}
+\mathbf{0} &= -\mathbf{G}'
+ + \mathbf{R}'\left(\mathbf{G}_c\mathbf{G}_c
+ - \mathbf{B}_c\mathbf{B}_c\right)
+ - \mathbf{X}'\left(\mathbf{G}_c\mathbf{B}_c
+ + \mathbf{B}_c\mathbf{G}_c\right) \\
+\mathbf{0} &= -\mathbf{B}'
+ + \mathbf{R}'\left(\mathbf{G}_c\mathbf{B}_c
+ + \mathbf{B}_c\mathbf{G}_c\right)
+ + \mathbf{X}'\left(\mathbf{G}_c\mathbf{G}_c
+ - \mathbf{B}_c\mathbf{B}_c\right)
+\end{aligned}
+```
+
+## Initialization
+
+Validate the full-conductor matrix dimensions. Initialize
+$\mathbf{G}_c$ and $\mathbf{B}_c$ from the current $\mathbf{R}'$,
+$\mathbf{X}'$, $\mathbf{G}'$, and $\mathbf{B}'$ inputs.
+
+## Model Outputs
+
+Symbol | Units | Description | Note
+------ | ----- | ----------- | ----
+$\mathbf{G}_c$ | [S] | Characteristic conductance | $\mathbb{R}^{K\times K}$
+$\mathbf{B}_c$ | [S] | Characteristic susceptance | $\mathbb{R}^{K\times K}$
diff --git a/GridKit/Model/EMT/Parameters/Response/Zc/README.md b/GridKit/Model/EMT/Parameters/Response/Zc/README.md
new file mode 100644
index 000000000..3a58c1437
--- /dev/null
+++ b/GridKit/Model/EMT/Parameters/Response/Zc/README.md
@@ -0,0 +1,105 @@
+# Zc Model
+
+`Zc` computes the full-conductor characteristic impedance from the
+per-unit-length series impedance and shunt admittance matrices.
+
+Notes:
+- For multiconductor lines, the V-definition and I-definition differ by the
+ ordering of the matrix products.
+- This model uses the V-definition: the shunt matrix pair multiplies
+ $\mathbf{Z}_c^2$ on the left.
+- The I-definition places the shunt matrix pair on the right.
+- The real and imaginary parts of $\mathbf{Z}_c$ are $\mathbf{R}_c$ and
+ $\mathbf{X}_c$.
+
+The characteristic impedance is decomposed as
+$\mathbf{Z}_c=\mathbf{R}_c+j\mathbf{X}_c$.
+
+The complex form typically given for this convention is:
+
+```math
+\mathbf{Z}_c =
+\sqrt{
+(\mathbf{G}' + j\mathbf{B}')^{-1}
+(\mathbf{R}' + j\mathbf{X}')
+}
+```
+
+## Model Parameters
+
+None. `Zc` combines full-conductor parameter outputs for $K$ physical
+conductors.
+
+### Parameter Validation
+
+The full-conductor inputs must be square and have the same dimension.
+
+### Model Derived Parameters
+
+None.
+
+## Model Variables
+
+### Internal Variables
+
+#### Differential
+
+None.
+
+#### Algebraic
+
+Symbol | Units | Description | Note
+------ | ----- | ----------- | ----
+$\mathbf{R}_c$ | [$\Omega$] | Characteristic resistance | $\mathbb{R}^{K\times K}$
+$\mathbf{X}_c$ | [$\Omega$] | Characteristic reactance | $\mathbb{R}^{K\times K}$
+
+### External Variables
+
+#### Differential
+
+None.
+
+#### Algebraic
+
+Symbol | Units | Description | Note
+------ | ----- | ----------- | ----
+$\mathbf{R}'$ | [$\Omega$/m] | Full-conductor resistance | from [`SeriesImpedance`](../../Effects/SeriesImpedance/README.md)
+$\mathbf{X}'$ | [$\Omega$/m] | Full-conductor reactance | $\omega\mathbf{L}'$ from [`SeriesImpedance`](../../Effects/SeriesImpedance/README.md)
+$\mathbf{G}'$ | [S/m] | Full-conductor shunt conductance | from [`ShuntAdmittance`](../../Effects/ShuntAdmittance/README.md)
+$\mathbf{B}'$ | [S/m] | Full-conductor shunt susceptance | $\omega\mathbf{C}'$ from [`ShuntAdmittance`](../../Effects/ShuntAdmittance/README.md)
+
+## Model Equations
+
+### Differential Equations
+
+None.
+
+### Algebraic Equations
+
+```math
+\begin{aligned}
+\mathbf{0} &= -\mathbf{R}'
+ + \mathbf{G}'\left(\mathbf{R}_c\mathbf{R}_c
+ - \mathbf{X}_c\mathbf{X}_c\right)
+ - \mathbf{B}'\left(\mathbf{R}_c\mathbf{X}_c
+ + \mathbf{X}_c\mathbf{R}_c\right) \\
+\mathbf{0} &= -\mathbf{X}'
+ + \mathbf{G}'\left(\mathbf{R}_c\mathbf{X}_c
+ + \mathbf{X}_c\mathbf{R}_c\right)
+ + \mathbf{B}'\left(\mathbf{R}_c\mathbf{R}_c
+ - \mathbf{X}_c\mathbf{X}_c\right)
+\end{aligned}
+```
+
+## Initialization
+
+Validate the full-conductor matrix dimensions. Initialize
+$\mathbf{R}_c$ and $\mathbf{X}_c$ from the current $\mathbf{R}'$,
+$\mathbf{X}'$, $\mathbf{G}'$, and $\mathbf{B}'$ inputs.
+
+## Model Outputs
+
+Symbol | Units | Description | Note
+------ | ----- | ----------- | ----
+$\mathbf{R}_c$ | [$\Omega$] | Characteristic resistance | $\mathbb{R}^{K\times K}$
+$\mathbf{X}_c$ | [$\Omega$] | Characteristic reactance | $\mathbb{R}^{K\times K}$
diff --git a/GridKit/Model/EMT/README.md b/GridKit/Model/EMT/README.md
index 0b3e15a00..e23413510 100644
--- a/GridKit/Model/EMT/README.md
+++ b/GridKit/Model/EMT/README.md
@@ -18,3 +18,11 @@ The current EMT documentation is organized into:
- `Component` (See [Component](Component/README.md))
- `Operators` (See [Operators](Operators/README.md))
+- `Parameters` (See [Parameters](Parameters/README.md))
+
+Component models are documented under `Component` because they are EMT models
+connected to buses. Reusable transfer and coordinate tools are documented under
+`Operators`.
+Frequency-domain line-parameter models are documented under `Parameters`
+because they generate sampled per-unit-length data rather than EMT bus
+residuals.
diff --git a/docs/Figures/EMT/Conductor/diagram.png b/docs/Figures/EMT/Conductor/diagram.png
new file mode 100644
index 000000000..7e8dc3495
Binary files /dev/null and b/docs/Figures/EMT/Conductor/diagram.png differ
diff --git a/docs/Figures/EMT/Conductor/diagram.tex b/docs/Figures/EMT/Conductor/diagram.tex
new file mode 100644
index 000000000..aadc3581f
--- /dev/null
+++ b/docs/Figures/EMT/Conductor/diagram.tex
@@ -0,0 +1,42 @@
+\documentclass[tikz,border=12pt]{standalone}
+\input{../../utils/gridkit.tex}
+\usetikzlibrary{patterns}
+
+\begin{document}
+\begin{tikzpicture}[gk]
+
+% =====================================================================
+% Tubular conductor cross-section: outer radius r_i, hollow bore q_i.
+% The metal annulus (section-hatched) carries the axial current
+% (out of page) and has material properties sigma_i, mu_i.
+% =====================================================================
+
+\def\rO{2.5} % outer radius (screen units)
+\def\rI{1.05} % inner (bore) radius
+\pgfmathsetmacro{\rM}{(\rO+\rI)/2} % mid-metal radius
+
+% ---- metal annulus: light tint + section hatch, hollow bore --------
+\fill[gkConductor!12] (0,0) circle (\rO);
+\fill[pattern=north east lines, pattern color=gkConductor!65] (0,0) circle (\rO);
+\fill[white] (0,0) circle (\rI);
+\draw[gkConductor, line width=1.9pt] (0,0) circle (\rO);
+\draw[gkConductor, line width=1.4pt] (0,0) circle (\rI);
+
+% ---- axial current carried in the metal (out of page) -------------
+\foreach \a in {0,90,180,270}{%
+ \fill[white] (\a:\rM) circle (4.2pt);
+ \draw[gkConductor, line width=0.8pt] (\a:\rM) circle (3.3pt);
+ \fill[gkConductor] (\a:\rM) circle (1.0pt);
+}
+
+% ---- geometry: outer radius r_i and inner radius q_i (right angle) --
+\gkradius{0}{0}{35}{\rO}{$r_i$}
+\draw[->, thin, gkSteel] (0,0) -- (125:\rI) node[pos=0.66, gkdimlbl]{$q_i$};
+\fill[gkSteel] (0,0) circle (1.7pt);
+
+% ---- material properties (leader out of the metal) ----------------
+\draw[gkSteel, thin] (235:\rM) -- (-2.65,-2.0)
+ node[left, gksig]{$\sigma_i,\ \mu_i$};
+
+\end{tikzpicture}
+\end{document}
diff --git a/docs/Figures/EMT/Path/diagram.png b/docs/Figures/EMT/Path/diagram.png
new file mode 100644
index 000000000..7d028e842
Binary files /dev/null and b/docs/Figures/EMT/Path/diagram.png differ
diff --git a/docs/Figures/EMT/Path/diagram.tex b/docs/Figures/EMT/Path/diagram.tex
new file mode 100644
index 000000000..d50a6d0ff
--- /dev/null
+++ b/docs/Figures/EMT/Path/diagram.tex
@@ -0,0 +1,162 @@
+\documentclass[tikz,border=0pt]{standalone}
+\input{../../utils/gridkit.tex}
+
+% =====================================================================
+% Path model: an ordered GIS route P_1,...,P_{Np} on the earth sphere.
+% Each interval P_n -> P_{n+1} contributes the great-circle (haversine)
+% arc length s_n = R_oplus c_n; the route is a smooth chain of geodesic
+% segments. The globe is an offset, cropped, soft-lit sphere.
+%
+% Orthographic projection; each segment is sampled by spherical linear
+% interpolation (slerp) of its endpoint unit vectors.
+% =====================================================================
+
+% modern globe palette (cool blue-gray, lit from upper-left)
+\definecolor{gkGlobeLo}{RGB}{237,243,248} % highlight (near-white)
+\definecolor{gkGlobeHi}{RGB}{151,174,196} % body / terminator
+\tikzset{gkgrid/.style = {white, line width=0.4pt, opacity=0.5}}
+
+\def\Rs{5.2} % sphere screen radius (large)
+\def\ox{2.7} % globe centre x (offset right)
+\def\oy{-1.3} % globe centre y (offset down)
+\def\vlat{16} % view latitude (deg)
+\def\vlon{20} % view longitude (deg)
+\def\Nseg{20} % samples per geodesic
+
+\begin{document}
+
+% ---- orthographic view basis (east, north, out) at (vlat,vlon) -----
+\pgfmathsetmacro{\eastx}{-sin(\vlon)}
+\pgfmathsetmacro{\easty}{ cos(\vlon)}
+\pgfmathsetmacro{\eastz}{0}
+\pgfmathsetmacro{\northx}{-sin(\vlat)*cos(\vlon)}
+\pgfmathsetmacro{\northy}{-sin(\vlat)*sin(\vlon)}
+\pgfmathsetmacro{\northz}{ cos(\vlat)}
+\pgfmathsetmacro{\outx}{cos(\vlat)*cos(\vlon)}
+\pgfmathsetmacro{\outy}{cos(\vlat)*sin(\vlon)}
+\pgfmathsetmacro{\outz}{sin(\vlat)}
+
+% project (lat,lon) -> screen (\sx,\sy); \sz>0 means front hemisphere
+\newcommand{\proj}[2]{%
+ \pgfmathsetmacro{\vX}{cos(#1)*cos(#2)}%
+ \pgfmathsetmacro{\vY}{cos(#1)*sin(#2)}%
+ \pgfmathsetmacro{\vZ}{sin(#1)}%
+ \pgfmathsetmacro{\sx}{\Rs*(\vX*\eastx+\vY*\easty+\vZ*\eastz)}%
+ \pgfmathsetmacro{\sy}{\Rs*(\vX*\northx+\vY*\northy+\vZ*\northz)}%
+ \pgfmathsetmacro{\sz}{\vX*\outx+\vY*\outy+\vZ*\outz}%
+}
+\newcommand{\waypoint}[3]{\proj{#2}{#3}\coordinate (#1) at (\sx,\sy);}
+
+% great-circle polyline between (lat1,lon1) and (lat2,lon2)
+\newcommand{\geoseg}[5]{% #1 lat1 #2 lon1 #3 lat2 #4 lon2 #5 style
+ \pgfmathsetmacro{\Ax}{cos(#1)*cos(#2)}%
+ \pgfmathsetmacro{\Ay}{cos(#1)*sin(#2)}%
+ \pgfmathsetmacro{\Az}{sin(#1)}%
+ \pgfmathsetmacro{\Bx}{cos(#3)*cos(#4)}%
+ \pgfmathsetmacro{\By}{cos(#3)*sin(#4)}%
+ \pgfmathsetmacro{\Bz}{sin(#3)}%
+ \pgfmathsetmacro{\dab}{min(1,max(-1,\Ax*\Bx+\Ay*\By+\Az*\Bz))}%
+ \pgfmathsetmacro{\Om}{acos(\dab)}%
+ \foreach \i in {0,...,\Nseg}{%
+ \pgfmathsetmacro{\tt}{\i/\Nseg}%
+ \pgfmathsetmacro{\wa}{sin((1-\tt)*\Om)/sin(\Om)}%
+ \pgfmathsetmacro{\wb}{sin(\tt*\Om)/sin(\Om)}%
+ \pgfmathsetmacro{\vX}{\wa*\Ax+\wb*\Bx}%
+ \pgfmathsetmacro{\vY}{\wa*\Ay+\wb*\By}%
+ \pgfmathsetmacro{\vZ}{\wa*\Az+\wb*\Bz}%
+ \pgfmathsetmacro{\px}{\Rs*(\vX*\eastx+\vY*\easty+\vZ*\eastz)}%
+ \pgfmathsetmacro{\py}{\Rs*(\vX*\northx+\vY*\northy+\vZ*\northz)}%
+ \coordinate (gc\i) at (\px,\py);%
+ }%
+ \draw[#5] (gc0) \foreach \i in {1,...,\Nseg}{ -- (gc\i)};%
+}
+
+% front-hemisphere parallel (lat = #1) and meridian (lon = #1)
+\newcommand{\parallelarc}[1]{%
+ \foreach \lo in {-180,-165,...,165}{%
+ \pgfmathsetmacro{\loB}{\lo+15}%
+ \proj{#1}{\lo}\edef\xa{\sx}\edef\ya{\sy}\edef\za{\sz}%
+ \proj{#1}{\loB}\edef\xb{\sx}\edef\yb{\sy}\edef\zb{\sz}%
+ \ifdim\za pt>0pt\ifdim\zb pt>0pt
+ \draw[gkgrid] (\xa,\ya) -- (\xb,\yb);\fi\fi}}
+\newcommand{\meridianarc}[1]{%
+ \foreach \la in {-75,-60,...,75}{%
+ \pgfmathsetmacro{\laB}{\la+15}%
+ \proj{\la}{#1}\edef\xa{\sx}\edef\ya{\sy}\edef\za{\sz}%
+ \proj{\laB}{#1}\edef\xb{\sx}\edef\yb{\sy}\edef\zb{\sz}%
+ \ifdim\za pt>0pt\ifdim\zb pt>0pt
+ \draw[gkgrid] (\xa,\ya) -- (\xb,\yb);\fi\fi}}
+
+\begin{tikzpicture}[gk]
+
+% fixed figure frame (defines crop + bounding box)
+\useasboundingbox (-4.6,-3.7) rectangle (4.6,3.7);
+
+\begin{scope}
+\clip (-4.6,-3.7) rectangle (4.6,3.7);
+\begin{scope}[shift={(\ox,\oy)}]
+
+ % ---- soft-lit sphere: body + diffuse highlight (upper-left) -------
+ \pgfmathsetmacro{\hlx}{-0.50*\Rs}
+ \pgfmathsetmacro{\hly}{ 0.52*\Rs}
+ \pgfmathsetmacro{\hlr}{ 1.35*\Rs}
+ \begin{scope}
+ \clip (0,0) circle (\Rs);
+ \fill[gkGlobeHi] (0,0) circle (\Rs);
+ \shade[inner color=gkGlobeLo, outer color=gkGlobeHi] (\hlx,\hly) circle (\hlr);
+ \end{scope}
+
+ % ---- graticule (front hemisphere) and crisp limb -----------------
+ \foreach \L in {-60,-30,0,30,60}{\parallelarc{\L}}
+ \foreach \L in {-60,-30,0,30,60,90}{\meridianarc{\L}}
+ \draw[gkGlobeHi!60!black, thin] (0,0) circle (\Rs);
+
+ % ---- smooth GIS route P_1 ... P_8 on the upper-left surface -------
+ \waypoint{P1}{36}{-24}
+ \waypoint{P2}{40}{-19}
+ \waypoint{P3}{42}{-14}
+ \waypoint{P4}{40}{ -9}
+ \waypoint{P5}{36}{ -4}
+ \waypoint{P6}{34}{ 1}
+ \waypoint{P7}{37}{ 5}
+ \waypoint{P8}{41}{ 10}
+
+ \geoseg{36}{-24}{40}{-19}{gkcond}
+ \geoseg{40}{-19}{42}{-14}{gkcond}
+ \geoseg{42}{-14}{40}{ -9}{gkcond}
+ \geoseg{40}{ -9}{36}{ -4}{gkcond}
+ \geoseg{36}{ -4}{34}{ 1}{gkcond}
+ \geoseg{34}{ 1}{37}{ 5}{gkcond}
+ \geoseg{37}{ 5}{41}{ 10}{gkcond}
+
+ \foreach \p in {P1,P2,P3,P4,P5,P6,P7,P8}{%
+ \fill[white] (\p) circle (3.4pt);
+ \fill[gkconddot] (\p) circle (2.6pt);}
+ \node[gksig, gkConductor, below=3pt] at (P1) {$P_1$};
+ \node[gksig, gkConductor, right=3pt] at (P8) {$P_{N_p}$};
+
+\end{scope}
+\end{scope}
+
+% ---- title / coordinate note (top-left, off the globe) -------------
+\node[gksig, gkConductor, anchor=north west] at (-4.4,3.5)
+ {$P_n=(\Phi_n,\Lambda_n)$};
+
+% ---- detail callout (lower-left): one segment's arc geometry -------
+\begin{scope}[shift={(-2.55,-1.95)}]
+ \def\ri{1.4}
+ \fill[white] (-1.55,-0.72) rectangle (1.55,2.18);
+ \draw[gkSteel, thin, rounded corners=3pt] (-1.55,-0.72) rectangle (1.55,2.18);
+ \draw[gkSteel, thin] (0,0) -- (110:\ri);
+ \draw[gkSteel, thin] (0,0) -- (70:\ri) node[pos=0.56, right=2pt, gksig, gkSteel]{$R_\oplus$};
+ \draw[gkcond, line width=1.6pt] (70:\ri) arc (70:110:\ri);
+ \node[gksig] at (90:\ri+0.28) {$s_n$};
+ \draw[thin, gkSteel] (70:0.55) arc (70:110:0.55);
+ \node[gksig, gkSteel] at (90:0.88) {$c_n$};
+ \fill[gkconddot] (110:\ri) circle (2.4pt) node[gkConductor, above left=-2pt and -2pt, gksig]{$P_n$};
+ \fill[gkconddot] ( 70:\ri) circle (2.4pt) node[gkConductor, above right=-2pt and -2pt, gksig]{$P_{n+1}$};
+ \fill[gkSteel] (0,0) circle (1.5pt) node[below=1.5pt, gksig]{$O$};
+\end{scope}
+
+\end{tikzpicture}
+\end{document}
diff --git a/docs/Figures/EMT/Tower/arrangement.png b/docs/Figures/EMT/Tower/arrangement.png
new file mode 100644
index 000000000..6012bcdf0
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diff --git a/docs/Figures/EMT/Tower/arrangement.tex b/docs/Figures/EMT/Tower/arrangement.tex
new file mode 100644
index 000000000..23199e6cd
--- /dev/null
+++ b/docs/Figures/EMT/Tower/arrangement.tex
@@ -0,0 +1,44 @@
+\documentclass[tikz,border=12pt]{standalone}
+\input{../../utils/gridkit.tex}
+
+\begin{document}
+\begin{tikzpicture}[gk]
+
+% =====================================================================
+% Three-phase + neutral conductor arrangement. Each conductor attaches
+% to the tower at coordinate (x_i, H_i) above the earth and carries a
+% phase label phi_i in {a,b,c,n}. H_i is the attachment height.
+% =====================================================================
+
+\def\Hp{3.4} % phase attachment height H_{a,b,c}
+\def\Hn{4.7} % neutral attachment height H_n
+\def\Ya{4.1} % crossarm level
+\def\xa{-2.5}\def\xb{0}\def\xc{2.5}
+
+% ---- earth ----------------------------------------------------------
+\gkground{-5.0}{5.2}{0}
+
+% ---- tower: mast, crossarm, shield peak ----------------------------
+\draw[gkSteel, line width=2.3pt] (0,0) -- (0,\Ya); % main mast
+\draw[gkSteel, line width=2.3pt] (0,\Ya) -- (0,\Hn); % shield peak
+\draw[gkSteel, line width=2.3pt] (-2.95,\Ya) -- (2.95,\Ya); % crossarm
+
+% ---- insulator strings + phase conductors --------------------------
+\foreach \x in {\xa,\xb,\xc}{\draw[gkSteel, thin] (\x,\Ya) -- (\x,\Hp);}
+\fill[gkconddot] (\xa,\Hp) circle (3.6pt);
+\fill[gkconddot] (\xb,\Hp) circle (3.6pt);
+\fill[gkconddot] (\xc,\Hp) circle (3.6pt);
+\fill[gkconddot] (0,\Hn) circle (3.6pt); % neutral at apex
+
+% ---- phase labels phi_i (relevant info) ----------------------------
+\node[gksig, gkConductor, below=3.5pt] at (\xa,\Hp) {$a$};
+\node[gksig, gkConductor, below right=0pt and 3pt] at (\xb,\Hp) {$b$};
+\node[gksig, gkConductor, below=3.5pt] at (\xc,\Hp) {$c$};
+\node[gksig, gkConductor, above right=0pt and 2.5pt] at (0,\Hn) {$n$};
+
+% ---- attachment height H_i above earth -----------------------------
+\draw[gkSteel, thin] (\xc,\Hp) -- (4.0,\Hp);
+\gkdimv{3.8}{0}{\Hp}{$H_i$}
+
+\end{tikzpicture}
+\end{document}
diff --git a/docs/Figures/EMT/Tower/diagram.png b/docs/Figures/EMT/Tower/diagram.png
new file mode 100644
index 000000000..3f60fb538
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diff --git a/docs/Figures/EMT/Tower/diagram.tex b/docs/Figures/EMT/Tower/diagram.tex
new file mode 100644
index 000000000..a37d77e53
--- /dev/null
+++ b/docs/Figures/EMT/Tower/diagram.tex
@@ -0,0 +1,36 @@
+\documentclass[tikz,border=12pt]{standalone}
+\input{../../utils/gridkit.tex}
+
+\begin{document}
+\begin{tikzpicture}[gk]
+
+% --- ground, supports, conductor -------------------------------------
+\gkground{-5.6}{5.6}{-1.1}
+\gkpole{-4}{-1.1}{1.687}
+\gkpole{ 4}{-1.1}{1.687}
+\gkcatenary{-4}{4}{5}
+
+% support-level chord and span-average (representative) level
+\draw[gkguide] (-4,1.687) -- (4,1.687);
+\draw[gkguide] (-4,0.551) -- (4,0.551);
+
+% --- span S (top) ----------------------------------------------------
+\draw[gkSteel, thin] (-4,1.687) -- (-4,2.62);
+\draw[gkSteel, thin] ( 4,1.687) -- ( 4,2.62);
+\gkdimh{-4}{4}{2.46}{$S$}
+
+% --- midspan sag D_i^sag --------------------------------------------
+\gkdimv{0}{1.687}{0}{$D_i^{\mathrm{sag}}$}
+
+% --- attachment height H_i (right) and representative height h_i -----
+\draw[gkSteel, thin] (4,1.687) -- (5.0,1.687);
+\gkdimv{4.8}{-1.1}{1.687}{$H_i$}
+\draw[gkSteel, thin] (-5.0,0.551) -- (-4,0.551);
+\gkdimv{-4.8}{-1.1}{0.551}{$h_i$}
+
+% attachment dots last (top z-order)
+\fill[gkSteel] (-4,1.687) circle (2.4pt);
+\fill[gkSteel] ( 4,1.687) circle (2.4pt);
+
+\end{tikzpicture}
+\end{document}
diff --git a/docs/Figures/EMT/Tower/images.png b/docs/Figures/EMT/Tower/images.png
new file mode 100644
index 000000000..01f4b6ebe
Binary files /dev/null and b/docs/Figures/EMT/Tower/images.png differ
diff --git a/docs/Figures/EMT/Tower/images.tex b/docs/Figures/EMT/Tower/images.tex
new file mode 100644
index 000000000..fe91e9dff
--- /dev/null
+++ b/docs/Figures/EMT/Tower/images.tex
@@ -0,0 +1,57 @@
+\documentclass[tikz,border=12pt]{standalone}
+\input{../../utils/gridkit.tex}
+
+\begin{document}
+\begin{tikzpicture}[gk]
+
+% =====================================================================
+% Method of images for the distance matrices. Conductors i, j sit at
+% representative heights h_i, h_j above the earth; their mirror images
+% i', j' lie at equal depth below it. The direct distance is D_ij and
+% the image distance D'_ij; d_ij is the horizontal separation.
+% D_ij = sqrt(d_ij^2 + (h_i - h_j)^2)
+% D'_ij = sqrt(d_ij^2 + (h_i + h_j)^2)
+% =====================================================================
+
+\coordinate (ci) at (-2.3, 3.0); % conductor i
+\coordinate (cj) at ( 2.6, 1.8); % conductor j
+\coordinate (cim) at (-2.3,-3.0); % image i'
+\coordinate (cjm) at ( 2.6,-1.8); % image j'
+
+% ---- earth (mirror plane) ------------------------------------------
+\gkground{-5.0}{5.2}{0}
+\node[gksig, gkSteel] at (-4.55,0.34) {earth};
+
+% mirror-correspondence guides
+\draw[gkguide] (ci) -- (cim);
+\draw[gkguide] (cj) -- (cjm);
+
+% ---- direct distance D_ij and image distance D'_ij -----------------
+\draw[gkSteel, semithick] (ci) -- (cj)
+ node[pos=0.5, above, gkdimlbl]{$D_{ij}$};
+\draw[gkimage] (ci) -- (cjm)
+ node[pos=0.78, gkdimlbl, text=gkImage]{$D'_{ij}$};
+
+% ---- horizontal separation d_ij ------------------------------------
+\draw[gkSteel, thin] (ci) -- (-2.3,3.7);
+\draw[gkSteel, thin] (cj) -- ( 2.6,3.7);
+\gkdimh{-2.3}{2.6}{3.55}{$d_{ij}$}
+
+% ---- representative heights h_i, h_j and mirrored image depths ------
+\draw[gkSteel, thin] (ci) -- (-3.7, 3.0);
+\draw[gkSteel, thin] (cim) -- (-3.7,-3.0);
+\gkdimv{-3.7}{0}{ 3.0}{$h_i$}
+\gkdimv{-3.7}{0}{-3.0}{$h_i$}
+\draw[gkSteel, thin] (cj) -- ( 4.3, 1.8);
+\draw[gkSteel, thin] (cjm) -- ( 4.3,-1.8);
+\gkdimv{4.3}{0}{ 1.8}{$h_j$}
+\gkdimv{4.3}{0}{-1.8}{$h_j$}
+
+% ---- conductors and images (top z-order) ---------------------------
+\fill[gkconddot] (ci) circle (3.4pt) node[above left =-1pt and 0pt, gkConductor, gksig]{$i$};
+\fill[gkconddot] (cj) circle (3.4pt) node[above right=-1pt and 0pt, gkConductor, gksig]{$j$};
+\fill[gkimagedot] (cim) circle (3.4pt) node[below left =-1pt and 0pt, gkImage, gksig]{$i'$};
+\fill[gkimagedot] (cjm) circle (3.4pt) node[below right=-1pt and 0pt, gkImage, gksig]{$j'$};
+
+\end{tikzpicture}
+\end{document}
diff --git a/docs/Figures/utils/gridkit.tex b/docs/Figures/utils/gridkit.tex
new file mode 100644
index 000000000..f1a5e8e96
--- /dev/null
+++ b/docs/Figures/utils/gridkit.tex
@@ -0,0 +1,108 @@
+%% =====================================================================
+%% gridkit.tex — shared TikZ utilities for GridKit documentation figures
+%% ---------------------------------------------------------------------
+%% Usage (from docs/Figures///diagram.tex):
+%%
+%% \documentclass[tikz,border=12pt]{standalone}
+%% \input{../../utils/gridkit.tex}
+%% \begin{document}
+%% \begin{tikzpicture}[gk]
+%% ...
+%% \end{tikzpicture}
+%% \end{document}
+%%
+%% Naming: colors gk, styles gk, macros \gk.
+%% `\documentclass[tikz,...]{standalone}` already loads TikZ; this file
+%% only adds packages, libraries, colors, styles, and macros.
+%%
+%% Extending this file:
+%% * New measurement -> add a \newcommand{\gk} in MACROS, keeping
+%% the signature {}{