Fixed bug when validating the grid resolution near

Author: dmarek-flex

CHANGELOG.md

@@ -34,6 +34,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Fixed handling of symmetry when creating adjoint field sources and added warning when broken up adjoint simulations do not have the same symmetry as the forward simulation.
 - Validation for `CustomGridBoundaries`, which was previously allowing unsorted arrays and arrays with less than two entries.
 - `DiffractionMonitor` results to apply finite grid field corrections for higher precision when comparing e.g. to `FluxMonitor` computations of total power.
+- Bug when validating the grid resolution near `CoaxialLumpedPort`.
 
 ### Changed
 - Relaxed bounds checking of path integrals during `WavePort` validation.

tests/test_plugins/smatrix/test_terminal_component_modeler.py

@@ -24,6 +24,8 @@
 from ...utils import run_emulated
 from .terminal_component_modeler_def import make_coaxial_component_modeler, make_component_modeler
 
+mm = 1e3
+
 
 def run_component_modeler(monkeypatch, modeler: TerminalComponentModeler):
     sim_dict = modeler.sim_dict
@@ -285,8 +287,27 @@ def test_run_coaxial_component_modeler(monkeypatch, tmp_path):
             )
 
 
-def test_coarse_grid_at_coaxial_port(monkeypatch, tmp_path):
-    modeler = make_coaxial_component_modeler(path_dir=str(tmp_path), port_refinement=False)
+@pytest.mark.parametrize(
+    "grid_spec",
+    [
+        None,
+        td.GridSpec(
+            grid_x=td.UniformGrid(dl=0.1 * mm),
+            grid_y=td.UniformGrid(dl=10 * mm),
+            grid_z=td.UniformGrid(dl=0.1 * mm),
+        ),
+        td.GridSpec(
+            grid_x=td.UniformGrid(dl=10 * mm),
+            grid_y=td.UniformGrid(dl=0.1 * mm),
+            grid_z=td.UniformGrid(dl=0.1 * mm),
+        ),
+    ],
+)
+def test_coarse_grid_at_coaxial_port(monkeypatch, tmp_path, grid_spec):
+    """Ensure that the grid is fine enough at the coaxial ports along the transverse dimensions."""
+    modeler = make_coaxial_component_modeler(
+        path_dir=str(tmp_path), port_refinement=False, grid_spec=grid_spec
+    )
     # Without port refinement the grid is much too coarse for these port sizes
     with pytest.raises(SetupError):
         _ = run_component_modeler(monkeypatch, modeler)

tidy3d/plugins/smatrix/ports/coaxial_lumped.py

@@ -384,7 +384,7 @@ def _check_grid_size(self, yee_grid: YeeGrid):
         """Raises :class:``SetupError`` if the grid is too coarse at port locations"""
         trans_axes = self.remaining_axes
         for axis in trans_axes:
-            e_component = "xyz"[trans_axes[0]]
+            e_component = "xyz"[axis]
             e_grid = yee_grid.grid_dict[f"E{e_component}"]
             coords = e_grid.to_dict[e_component]
             min_bound = self.center[axis] - self.outer_diameter / 2