# Patch Antenna Diagnostics

Channel: release; package: 1.8.0; source: 7d1e97331656dd74ad0f5471653ac0c5effdff70

Page: https://remilab.ai/rfx/versions/v1.8.0/gallery/patch_antenna/
Source: https://github.com/bk-squared/rfx/blob/7d1e97331656dd74ad0f5471653ac0c5effdff70/docs/public/gallery/patch_antenna.mdx

## Status

These files are for **diagnosis**, not a validated patch-antenna result.
Do not cite the plotted S11 dip, field pattern, resonance label, match, Q, or
convergence as RF evidence.

The artifact-generating port configuration does not pass the current preflight:
the wire-port midpoint overlaps PEC, the feed is reported in PEC, the conductor
and feed gap are under-resolved, and the generator bypassed those findings with
`skip_preflight=True`. A finite S11 array or an AD/FD agreement does not repair
that physical setup.

## What the files show

The bundle records a finite-ground FR4 patch geometry, a one-port frequency
sweep, field visualizations, Touchstone export, and a material-permittivity
AD/finite-difference comparison. The assets are retained to inspect file formats
and plotting behavior:

- `geometry.png` — rendered geometry from the artifact setup;
- `field_resonance.png` and `field_anim.gif` — field visualizations from a
  separate soft-source run;
- `s11_db.png`, `sparams.json`, and `sparams.s1p` — output from the port setup
  that fails current preflight;
- `autodiff.png` and `gradient.json` — internal derivative consistency for that
  same numerical objective.

The soft-source field run and the port sweep are separate simulations. Their
images do not establish that a return-loss dip and a ring-down mode came from
one self-consistent run. No committed mesh and absorber convergence study supports
the displayed frequency.

![Patch geometry diagnostic](https://remilab.ai/rfx/versions/v1.8.0/gallery/assets/patch_antenna/geometry.png)

![Patch S11 diagnostic from a setup that fails preflight](https://remilab.ai/rfx/versions/v1.8.0/gallery/assets/patch_antenna/s11_db.png)

[Diagnostic Touchstone file](https://remilab.ai/rfx/versions/v1.8.0/gallery/assets/patch_antenna/sparams.s1p)

## Interpreting the AD/FD panel

The stored AD and central finite-difference values agree for the implemented
objective. This checks differentiation of that computation only. Because the
port geometry fails current preflight, the derivative must not be described
as patch sensitivity, matching sensitivity, or an antenna-design gradient.

![Internal AD/FD consistency diagnostic](https://remilab.ai/rfx/versions/v1.8.0/gallery/assets/patch_antenna/autodiff.png)

## Use a supported path

- [Your First Patch Antenna](https://remilab.ai/rfx/versions/v1.8.0/guide/first-patch/) gives a model that passes
  preflight and separates a short execution check from RF evidence.
- From a source checkout, `validation/crossval/05_patch_antenna.py` runs the
  repository's separate rfx/OpenEMS comparison. Its result applies only to the
  script's own geometry, mesh, metric, band, and tolerances; it does not
  reproduce this gallery bundle.
- [Cross-Validation and Accuracy](https://remilab.ai/rfx/versions/v1.8.0/guide/validation/) defines the evidence
  required before publishing resonance, S-parameter, or Q claims.

Computed with rfx 1.6.5 · 1eb551b · generated 2026-06-30T03:21:23Z