Ebrake1

Patch antenna with planar radome

This fixture pairs a 40 mm x 30 mm two-layer FR-4 patch board with one explicit external dielectric object. The board copper and stackup are in patch_with_radome.kicad_pcb; the radome is intentionally kept outside the PCB file in antenna_with_radome_run.json so it can be passed as solver input.

bare_antenna_run.json and antenna_with_radome_run.json define a paired bare-versus-radome experiment on exactly the same board, feed, frequency sweep, and requested mesh size. The latter keeps parameters.surrounding_geometry inline with the solver parameters. For the radome case, its first corner is (95, 95, 10) mm and its dimensions are (50, 40, 1.5) mm. The board occupies x=100..140 mm and y=100..130 mm. The solver coordinate system uses the top copper as z=0; positive z points into the air in front of the antenna. The slab therefore begins 10 mm above the top copper and ends at 11.5 mm.

epsilon_r: 2.1 is an explicit fixture input. No loss tangent is present because the current surroundings contract and EMerge adapter do not transfer external dielectric loss. Do not use a lossless result to make radome transmission, gain, pattern, or compliance claims.

The object uses the spike/emerge-surroundings/v1 contract:

{
  "kind": "dielectric_box",
  "name": "Radome slab",
  "origin_mm": [95, 95, 10],
  "size_mm": [50, 40, 1.5],
  "epsilon_r": 2.1
}

This is a planar surrogate, not a curved radome or a complete vehicle, enclosure, bracket, cable, connector, fastener, or ground-plane model. Any comparison between the bare and radome cases still needs mesh convergence, boundary checks, material characterization, and measurement correlation.

Reproduce and inspect the paired result

From the repository root with EMerge 3.0.0a19 installed in .venv-emerge3:

python scripts/run_emerge_antenna_example.py --config examples/emerge/radome/bare_antenna_run.json --python-executable .venv-emerge3/Scripts/python.exe --output-dir examples/emerge/radome --output-prefix bare
python scripts/run_emerge_antenna_example.py --config examples/emerge/radome/antenna_with_radome_run.json --python-executable .venv-emerge3/Scripts/python.exe --output-dir examples/emerge/radome --output-prefix covered
python scripts/compare_emerge_radome.py

Both seven-frequency runs completed through SPIKE's isolated extension host with model_status: unvalidated; their saved results are bare_result.json and covered_result.json. The comparison_evidence.json checks identical board, port, frequency and requested mesh inputs. At 3.4 GHz, S11 was -3.53 dB bare and -4.02 dB covered. At 3 GHz, the independently peak-normalized relative field sample at theta 180°, phi 0° changed from -9.94 to -11.93 dB. This angular difference is a change in normalized pattern shape, not radome insertion loss or absolute gain.

The paired S11 and angular-cut figure and interpolated 3D covered pattern are saved display artifacts. The 3D surface bilinearly interpolates relative linear amplitude from the solver's 13 × 25 angular grid to 5° spacing. SPIKE offers the same display interpolation, the original solved grid, and a relative pattern overlay in the EMI chamber. Its bench can be shown, made translucent, or hidden without changing the FEM case. None of those display choices creates new solved field values.