Antenna Integration and Deployment

Integrate designed antennas into RF systems -- impedance matching, data exchange via measuredAntenna, RF propagation/site planning, and SAR compliance -- using MATLAB Antenna Toolbox and RF Toolbox.

When to Use

Impedance matching

• Match an antenna to 50 ohm (or other impedance)
• Improve return loss or VSWR
• Design L, Pi, or Tee matching network
• Convert lumped matching to distributed (Richards transformation)
• Compare 2-element vs 3-element bandwidth

Measured antenna creation

• Create a measuredAntenna from pattern data or simulation
• Use an antenna with txsite/rxsite for propagation
• Import antenna data from CST (.ffs) or HFSS (.ffd)
• Steer a beam with phase shifts on a measured array
• Use a measuredAntenna as element in a larger array

RF propagation and site planning

• Compute signal strength, coverage, or path loss between sites
• Analyze SINR, interference, or frequency reuse
• Perform ray tracing for 5G/mmWave propagation
• Determine link budget or link closure
• Plan wireless network transmitter/receiver placement

SAR estimation

• Compute SAR from an antenna near or inside biological tissue
• Assess RF exposure compliance (FCC/ICNIRP limits)
• Model a birdcage coil for MRI SAR analysis
• Compute point SAR or mass-averaged SAR (1g/10g)
• Design an implantable antenna and estimate SAR

When NOT to Use

• Designing antenna elements or arrays (geometry, optimization) -- use matlab-design-antennas
• Reflector antennas, reflectarrays, installed antennas, or RCS -- use matlab-analyze-antenna-structures

Must-Follow Rules

Matching Networks

• Set CenterFrequency BEFORE LoadImpedance for frequency-dependent loads -- errors otherwise
• Property is Bandwidth not BandWidth -- case-sensitive
• addEvaluationParameter requires all 5 args: parameter, comparison, targetdB, band, weight
• Prefer sparameters(ant, freqRange) as load over raw antenna object (avoids repeated EM solves)
• Default to Components = 2 unless fractional BW > 5% (then use 3)

Measured Antennas

• Always transpose after meshgrid for az-fast ordering -- silently wrong patterns otherwise
• txsite/rxsite require E = [] -- errors if E-field data is present
• Only patternMultiply works when measuredAntenna is the Element of an array (not pattern)
• CalculateTotalField = true is required for EmbeddedE workflow
• EHfields returns 3-by-P -- transpose to P-by-3 for measuredAntenna

RF Propagation

• Do not call show(tx) in headless environments -- use analysis functions directly
• sigstrength(rxArray, txArray, pm) returns numTX-by-numRX matrix
• pathloss with ray tracing returns cell arrays -- sum powers in linear domain
• SurfaceMaterial is for cartesian scenes; BuildingsMaterial/TerrainMaterial for geographic
• Ray tracing requires buildings or scene data -- no value without geometry

SAR

• EHfields expects 3-by-M -- pass obsPoints'
• dielectric class enforces LossTangent <= 0.03 -- only birdcage.Phantom and direct EHfields bypass
• Always validate SAR with power balance check (efficiency vs SAR integral)
• Always normalize to a known input power (typically 1W accepted)
• conformalArray rejects intersecting geometries -- cannot place antenna inside tissue

Workflow

1. Impedance Matching

1. Parse -- Identify load (antenna, impedance, file), frequency, bandwidth, topology
2. Create -- Set CenterFrequency FIRST, then LoadImpedance, Bandwidth, Components
3. Evaluate -- addEvaluationParameter for gammain or Gt goals
4. Inspect -- circuitDescriptions returns ranked candidates
5. Visualize -- rfplot (S11/gain), smithplot (impedance transformation)
6. Export -- exportCircuits for RF Toolbox circuit; richards for distributed elements

2. Measured Antenna Creation

1. Parse -- Identify source antenna/array, frequency, intended use case
2. Select workflow -- E-field, Directivity-only, EmbeddedE, element-in-array, or ffsReader
3. Generate grid -- Spherical grid with correct transpose for az-fast ordering
4. Extract data -- EHfields (3-by-P, transpose to P-by-3) or pattern (el-by-az, transpose)
5. Build -- Construct measuredAntenna with correct property combination
6. Verify -- Compare pattern against original antenna/array

3. RF Propagation & Site Planning

1. Parse -- Identify analysis type (coverage, SINR, ray tracing, link budget), frequency, environment
2. Create sites -- txsite/rxsite with location, antenna, frequency, power
3. Select model -- Choose propagation model based on environment
4. Analyze -- sigstrength, coverage, sinr, raytrace, or los
5. Report -- Signal strength (dBm), path loss (dB), SINR (dB), link margin

4. SAR Estimation

1. Select approach -- birdcage+Phantom, conformalArray+Custom3D, or direct EHfields
2. Build tissue model -- Phantom struct, shape.Custom3D with catalog material, or post-processing
3. Compute E-fields -- EHfields(ant, freq, obsPoints') (3-by-M format)
4. Calculate SAR -- Apply formula with tissue sigma and rho; normalize to input power
5. Validate -- Power balance check (efficiency method vs SAR integral)

Key Classes

| Class | Purpose | |-------|---------| | matchingnetwork | L/C matching network synthesis and ranking | | measuredAntenna | Wraps field/pattern data for interoperability | | txsite / rxsite | Transmitter/receiver sites for propagation | | propagationModel | Path loss model selection (freespace, raytracing, etc.) | | propagationData | Import/visualize RF measurement data | | siteviewer | Map visualization (geographic or cartesian) | | birdcage | MRI coil with Phantom support | | conformalArray | Arbitrary element positions (antenna + dielectric body) | | shape.Custom3D | Passive dielectric scatterer for SAR | | ffsReader | Import CST .ffs far-field data (R2026a+) |

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 (pattern, show, rfplot, smithplot)
• Do add titles to manual plot, scatter3, imagesc figures
• Do not call show(tx) without siteviewer in headless environments
• 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 a matching network (topologies, evaluation, export, Richards) | references/matching-networks.md | | Creating measuredAntenna (E-field, directivity, EmbeddedE, ffsReader, HFSS) | references/measured-antennas.md | | RF propagation, coverage, SINR, ray tracing, link budget, path loss | references/rf-propagation.md | | Computing SAR (birdcage, conformalArray, EHfields, power balance) | references/sar-estimation.md |

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