Antenna Structure Design and Analysis

Design, analyze, and visualize electrically large antenna structures — reflector antennas, reflectarrays/RIS, platform-installed antennas, and radar cross section — using MATLAB Antenna Toolbox with appropriate EM solvers for each problem class.

When to Use

Reflector antennas

• Design a parabolic dish, satellite dish, or prime-focus reflector
• Design a Cassegrain or Gregorian dual-reflector system
• Design an offset-fed reflector (no blockage)
• Design a corner reflector, cylindrical or spherical reflector
• Use reflectorCalculator for trade studies
• Import custom reflector geometry from STL files

Reflectarrays and RIS

• Design a reflectarray antenna with unit cell phase control
• Design a reconfigurable intelligent surface (RIS) with quantized phases
• Characterize unit cell reflection phase (S-curve)
• Synthesize an aperture phase distribution for beam steering
• Verify pattern via pattern multiplication

Installed antennas on platforms

• Mount an antenna on a vehicle, aircraft, ship, satellite, or large structure
• Analyze installed antenna patterns, coupling, or efficiency
• Load platform geometry from STL/STEP/IGES files
• Generate platform geometry programmatically

Radar cross section

• Compute monostatic or bistatic RCS
• Analyze RCS of a platform, antenna, or array
• Compare RCS across polarizations (HH, VV, HV, VH)
• Compute RCS of a dielectric target

When NOT to Use

• Designing standalone antenna elements or arrays (no platform) — use matlab-design-antenna
• Optimizing antenna dimensions with SADEA/TR-SADEA — use matlab-design-antenna
• Impedance matching, measured antenna objects, RF propagation, or SAR — use matlab-integrate-antenna
• A flat reflector backing a dipole — use matlab-design-antenna (catalog element)

Must-Follow Rules

Reflectors

• Set Exciter BEFORE design() — design(obj, freq) takes two arguments only for reflectors
• cavity is NOT a valid exciter — it will error
• reflectorCorner and reflectorCylindrical have no SolverType property — always MoM
• Array as exciter: design the array first, assign to Exciter, do NOT call design() on reflector afterward

Reflectarrays

• infiniteArray only supports pcbStack with exactly 3 layers (metal-dielectric-metal)
• Set BoardThickness before Layers on pcbStack — order matters
• Feed offset: Use [Lp/4, 0, 1, 3] — not [0 0 1 3]
• Always unwrap phase with unwrap() and normalize magnitude (peak = 1)
• Pattern multiplication adds dB — element pattern (dB) + array factor (dB), NOT linear multiplication

Installed Antennas

• installedAntenna only supports pure metal antennas — no dielectric substrates
• Platform Units must be explicit — defaults to "mm" but ElementPosition is always in meters
• Set ElementPosition before Element for multi-element setups
• Always mesh explicitly before analysis — uncontrolled density causes inaccurate results

RCS

• One of azimuth or elevation must be scalar for monostatic sweeps
• Dielectric targets require FMM solver — PO and MoM will error
• UseFileAsMesh = true required for dielectric .mat files
• PO fails at grazing incidence — returns artificially low values (~-250 dBsm)

Solver Selection (All Workflows)

• Default: MoM-PO for installed/reflectors, PO for RCS
• Use FMM for: closed bodies, concave features, dielectric targets
• Verify FMM convergence with solver() then convergence() after analysis
• Mesh density: lambda/10 for MoM/FMM, lambda/6 for MoM-PO, default for PO

Workflow

1. Reflector Antenna Design

1. Parse — Identify reflector type, frequency, exciter, f/D ratio, constraints
2. Create — Set exciter first (if non-default), then call design(obj, freq)
3. Customize — Adjust Radius, FocalLength, FeedOffset for custom f/D
4. Analyze — Pattern, gain, beamwidth, impedance
5. Report — Key metrics with units, f/D ratio, aperture in wavelengths

For trade studies, use reflectorCalculator first (instant), then createAntenna for full-wave.

2. Reflectarray / RIS Design

1. Design unit cell — Parameterized pcbStack (3 layers) with variable patch size
2. Characterize S-curve — Sweep patch size via planeWaveExcitation + infiniteArray + EHfields
3. Synthesize aperture phase — Compute required phase (path delay + beam steering gradient)
4. Map phase to geometry — Invert S-curve via interpolation; quantize for RIS
5. Build geometry — conformalArray with unique elements at each position
6. Verify pattern — Element pattern + array factor via patternCustom

3. Installed Antenna Analysis

1. Create platform — Load from STL/STEP/IGES or generate programmatically
2. Install element(s) — Set Platform, ElementPosition, Element, SolverType
3. Mesh — mesh(ant, MaxEdgeLength=lambda/N) per solver guidelines
4. Analyze — Pattern, impedance, S-parameters (coupling), efficiency
5. Report — Metrics with units; verify FMM convergence if used

4. RCS Analysis

1. Create target — Load platform from file or use antenna/array object directly
2. Select solver — PO (default, fast), MoM (small, accurate), FMM (dielectric/concave)
3. Compute — rcs(obj, freq, az, el, Polarization=..., Solver=...)
4. Report — Peak RCS (dBsm), angular location, polarization

Key Classes

Class	Purpose
reflectorParabolic	Prime-focus parabolic dish
cassegrain / gregorian	Symmetric dual-reflector systems
cassegrainOffset / gregorianOffset	Offset dual-reflector (no blockage)
reflectorCorner	Corner reflector (90/60/45 deg)
reflectorCylindrical / reflectorSpherical	Fan-beam / wide-scan reflectors
customDualReflectors	Custom STL reflector surfaces
reflectorCalculator	Gaussian-beam analytical design (R2026a)
installedAntenna	Antenna mounted on conducting platform
platform	3D geometry loader (STL/STEP/IGES)
infiniteArray	Periodic boundary conditions for unit cells
planeWaveExcitation	Plane wave illumination for S-curve/RCS
conformalArray	Arbitrary element positions (reflectarray geometry)
pcbStack	Unit cell structure (3-layer for reflectarrays)
rcs	Radar cross section function

Conventions

Coding Standards

• 4-space indentation, lowerCamelCase variables, UpperCamelCase Name-Value args
• "double quotes" for strings, fprintf for formatted output
• Do not add titles to Antenna Toolbox plots (show, pattern, rcs auto-plot)
• Do add titles to manual plot, imagesc, subplot, and TitleTop to polarpattern
• Show all plots in separate figures. Include units in all output.

Script-First Workflow

For design, analysis, or sweep tasks — write code to .m files, run via run_matlab_file, iterate by editing and re-running. Use inline evaluate_matlab_code for quick one-off checks.

References

Load when...	Reference
Designing any reflector antenna (parabolic, dual, corner, custom STL)	references/reflector-antennas.md
Designing a reflectarray or RIS (unit cells, S-curve, phase synthesis)	references/reflectarrays.md
Installing antennas on platforms (STL loading, multi-element, conformalArray workaround)	references/installed-antennas.md
Computing monostatic/bistatic RCS (polarization, dielectric targets, GPU)	references/rcs-analysis.md
Choosing between MoM-PO, PO, MoM, FMM for any application	references/solver-selection.md

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