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matlab-integrate-antennas

Design & creation

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Updated 10-16 00:21

About this skill

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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