V1.2.2

SpecterCS v1.2.2

Changes:

• Bug Fixes (see fixes)

Fixes:

• Rewrote FacetContribution to use a new exact planar-polygon phase integral.
• Replaced TrianglePhaseIntegral with a Stokes'-theorem-based boundary integral.
• Added broadside limit handling for constant-phase facets.
• Replaced EdgeIntegral with EdgeTerm for better edge weighting and degenerate case handling.

Known Issues:

• OBJ files still return inflated RCS values due to OBJ file limitations, recommended users only use STL files.
• On first load, the RCS values will still be impossibly high. Use elevation slider to reset to realistic values (Cause unknown at time of v1.2.2 release).

Planned additions:

• Bi-Directional Multiphysics Coupling (EM-Thermal-Fluid)
• Non-Linear, Spatially-Variant Surface Impedance ($Z_s$) Boundaries
• Fluidic-Embedded Substrate Homogenization
• High-G Dynamic Loading Deformable Mesh
• Quantum Capacitance ($C_q$) Graphene Models.
• Galinstan Oxidation Layer Modeling

Use:

1. Unzip archive
2. Enter produced folder
3. Navigate to Echo1.Wpf.exe (DO NOT REMOVE FROM FOLDER)
4. Run

Full Changelog: v1.2.1...v1.2.2

v1.2.1

SpecterCS v1.2.1

Changes:

Added following options for material selections:

• Aluminium
• Titanium Alloy

Fixes:

• None

Known Issues:

• OBJ files still return inflated RCS values due to OBJ file limitations, recommended users only use STL files.
• On first load, the RCS values will be impossibly high. Use elevation slider to reset to realistic values.

Use:

1. Unzip archive
2. Enter produced folder
3. Navigate to Echo1.Wpf.exe (DO NOT REMOVE FROM FOLDER)
4. Run

Full Changelog: V1.1.1...v1.2.1

v1.1.1

SpecterCS v1.1.1

Release type: Patch
Breaking changes: None (behavioral corrections only)

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Fixed

Physical Optics (PO) Normalization

• Corrected PO amplitude scaling to remove unphysical frequency-squared amplification.
• Ensured RCS scales correctly with physical area, frequency, and aspect angle.
• Eliminated runaway RCS values on large smooth surfaces.

UTD Edge Diffraction Stability

• Switched edge diffraction accumulation from coherent amplitude summation to incoherent power summation.
• Removed erroneous edge-length scaling from the diffraction kernel.
• Added illumination and observer-visibility gating to suppress invalid edge contributions.
• Suppressed grazing-incidence singularities where UTD asymptotics are not valid.

Aspect Angle and Orientation Handling

• Aligned radar azimuth/elevation convention with aircraft body axes.
• Corrected default load orientation so Azimuth = 0°, Elevation = 0° corresponds to nose-on illumination.
• Restored physically correct large RCS variation with aspect angle (nose-on vs side-on vs broadside).

Mesh Import and Geometry Robustness

• Validated STL import path for consistent metric interpretation.
• Confirmed clean STL geometry produces stable and repeatable RCS results.
• Identified malformed or non-manifold OBJ meshes as a major source of prior instability and overestimation.

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Behavior Changes (Expected)

• Large changes in RCS with orientation are now normal and physically correct.
• PO dominates large, smooth surfaces; edge diffraction is secondary and bounded.
• Perfectly conducting aircraft models represent theoretical upper-bound RCS values.
• Clean STL meshes are strongly recommended for electromagnetic analysis.

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Notes

This release completes the transition from unstable or misleading RCS output to a physically consistent high-frequency PO+UTD solver. Remaining discrepancies with real-world measurements are attributable to idealized materials and geometry, not solver errors.

Future work will focus on realism enhancements such as material losses, intake masking, and cavity attenuation.

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Full Changelog: V1.1.0...V1.1.1

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Use:

1. Unzip archive
2. Enter produced folder
3. Navigate to Echo1.Wpf.exe (DO NOT REMOVE FROM FOLDER)
4. Run

V1.1.0

SpecterCS 1.1.0 Release Notes

Core Physics and Kernel Corrections

• Amplitude Scaling Fix
  Resolved a fundamental error where the ( k^2 ) factor was missing from the scattering amplitude. Radar Cross Section (RCS) values now scale correctly with frequency.

• Analytic Phase Integration
  Replaced the simplified centroid-only phase approximation with the Ling–Lee–Chuang (1989) analytic triangle integral to ensure accuracy for facets larger than ( \lambda / 4 ).

• UTD Rewrite
  Replaced the original edge diffraction logic with a complete implementation of the Kouyoumjian–Pathak (1974) Uniform Theory of Diffraction (UTD).

• Singularity Handling
  Integrated a Fresnel transition function using series expansion and Gauss–Legendre quadrature to prevent divergences at shadow and reflection boundaries.

• Polarization Logic
  Added full VV, HH, and HV polarization support with appropriate reflection sign conventions for both PEC and dielectric surfaces.

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Material and Radar Absorbent Coatings

• Complex Impedance Model
  Introduced a material model supporting complex permittivity (( \epsilon_r )) and permeability (( \mu_r )).

• RAM Integration
  Added single-layer Fresnel reflection coefficients for radar absorbent materials, including carbon foam and ferrite tiles.

• Assignment Tools
  Implemented per-facet material overrides and region-based material assignment using bounding box coordinates.

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Engine and UI Improvements

• Race Condition Resolution
  Fixed a multi-threading bug in the RCS engine where edge diffraction contributions were erroneously multiplied by the number of active worker threads.

• Geometric Reliability
  Replaced hash-based edge detection with 64-bit integer quantization to prevent vertex collisions and mesh corruption.

• Analysis Automation
  Added background task support for full 100-point azimuth and frequency sweeps.

• Data Visualization
  The interface now provides a separate breakdown of Physical Optics (PO) versus edge diffraction contributions and supports CSV data export.

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Future Work

Current limitations include:

• Single-bounce-only Physical Optics (PO) engine
• Single-layer material coatings

Multi-bounce Shooting and Bouncing Rays (SBR) and multilayer Transfer Matrix Method (TMM) support are planned for Phase 3.

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Full Changelog: V1.0.0...V1.1.0

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Use:

1. Unzip archive
2. Enter produced folder
3. Navigate to Echo1.Wpf.exe (DO NOT REMOVE FROM FOLDER)
4. Run

v1.0.0

V1.0.0 release

Full Changelog: https://github.com/n0m4official/Radar-Cross-Section-Simulation/commits

Use:

1. Unzip archive
2. Enter produced folder
3. Navigate to Echo1.Wpf.exe
4. Run