matlab-manage-pcb-material

# Managing Materials for RF PCB Toolbox

## When to Use

- Creating dielectric substrates for transmission lines, filters, couplers, or custom pcbComponent designs
- Selecting metals (Copper, Gold, etc.) for realistic conductor loss modeling
- Building multi-layer dielectric stacks for stripline or embedded designs
- Choosing frequency-dependent dispersion models (DjordjevicSarkar) for wideband accuracy
- Looking up catalog material properties or adding custom materials

## When NOT to Use

- Building the PCB layer structure itself — use `matlab-assemble-pcb-layout`
- Running EM analysis after materials are defined — use `matlab-analyze-em`
- Designing transmission lines that happen to need substrates — use `matlab-design-pcb-txline` (it references this skill for material details)
- Importing material properties from an existing board file — use `matlab-read-pcb-layout`

## Typical Workflow

1. **This skill:** Define substrate, conductor, and stackup — typically the first step in any RF PCB design
2. **After:** Any design skill (`matlab-design-pcb-filter`, `matlab-design-pcb-txline`, `matlab-assemble-pcb-layout`, `matlab-model-via`) — pass materials to the component

## Quick Reference

| Task | Code |
|------|------|
| Catalog dielectric | `sub = dielectric("FR4")` |
| Custom dielectric | `sub = dielectric(Name="MyMat", EpsilonR=4.4, LossTangent=0.02, Thickness=1.6e-3)` |
| Multi-layer dielectric | `sub = dielectric("FR4","Teflon"); sub.Thickness = [0.8e-3 0.4e-3]` |
| Catalog metal | `cond = metal("Copper")` |
| Custom metal | `cond = metal(Name="MyMetal", Conductivity=5.8e7, Thickness=35e-6)` |
| Browse dielectrics | `DielectricCatalog` |
| Browse metals | `MetalCatalog` |
| Frequency-dependent | `sub = dielectric(..., Frequency=1e9)` |
| Get properties at freq | `[epsr, tand, f] = getMaterialProperties(sub, freqVector)` |

## Creating Dielectrics

The `dielectric` object defines substrate properties. Create from the built-in catalog or specify custom parameters.

### From Catalog

```matlab
sub = dielectric("FR4");
sub = dielectric("Teflon");
sub = dielectric("RO4730JXR");
sub = dielectric("TMM10");
```

To see every name in the catalog:

```matlab
dc = DielectricCatalog;
disp(dc.Materials)
```

Available catalog names (R2026a): Air, FR4, Teflon, Foam, Polystyrene, Plexiglas, Fused quartz, E glass, RO4725JXR, RO4730JXR, TMM3, TMM4, TMM6, TMM10, TMM10i, Taconic RF-35. Add custom materials with `add(dc, ...)` if your material is not listed.

### Custom Properties

```matlab
sub = dielectric(Name="Rogers4350B", EpsilonR=3.66, LossTangent=0.0037, Thickness=0.508e-3);
```

### Key Properties

| Property | Description | Units |
|----------|-------------|-------|
| `Name` | Material identifier | string |
| `EpsilonR` | Relative permittivity | dimensionless |
| `LossTangent` | Dielectric loss tangent (tan δ) | dimensionless |
| `Thickness` | Layer thickness | meters |
| `Frequency` | Reference frequency for loss tangent | Hz |
| `FrequencyModel` | `'Constant'`, `'DjordjevicSarkar'`, `'MeanDjordjevicSarkar'`, or `'TableDriven'` | — |

### Browsing the Catalog

```matlab
dc = DielectricCatalog;
open(dc)               % Opens interactive catalog viewer
disp(dc.Materials)     % List all materials as a table
s = find(dc, "FR4");   % Returns struct with Name, Relative_Permittivity, Loss_Tangent, Frequency, Comments
```

## Creating Metals

The `metal` object defines conductor properties.

### From Catalog

```matlab
cond = metal("Copper");       % Conductivity=5.96e7, Thickness=35.56e-6 (1 oz)
cond = metal("Aluminium");    % Conductivity=3.77e7, Thickness=762e-6
cond = metal("Gold");         % Conductivity=4.11e7, Thickness=0.2e-6
```

Available catalog metals (R2026a): PEC, Copper, Aluminium, Gold, Silver, Zinc, Tungsten, Lead, Iron, Steel, Brass.

### Custom Properties

```matlab
cond = metal(Name="ThickCopper", Conductivity=5.8e7, Thickness=70e-6);
```

### Browsing the Catalog

```matlab
mc = MetalCatalog;
open(mc)                    % Opens interactive catalog viewer
disp(mc.Materials)          % List all metals as a table
s = find(mc, "Aluminium");  % Returns struct with Name, Conductivity, Thickness, Units, Comments
```

### Assigning to Components

```matlab
mline = microstripLine;
mline.Conductor = metal("Copper");
```

## Multi-Layer Substrates

Many RF PCB components support multi-layer dielectric stacks. Pass multiple material names or use vector properties.

### Shorthand Syntax (catalog names)

```matlab
sub = dielectric("FR4", "Teflon");
sub.Thickness = [0.0016 0.0008];
```

### Explicit Multi-Layer

```matlab
sub = dielectric(Name={"FR4","Foam","FR4"}, ...
    EpsilonR=[4.4 1.05 4.4], ...
    LossTangent=[0.02 0.001 0.02], ...
    Thickness=[0.4e-3 0.8e-3 0.4e-3]);
```

**Important**: Use a cell array `{...}` for `Name`, not a string array `[...]`. String array concatenation (`["FR4","Foam"]`) produces a single string `"FR4Foam"`, not a multi-element array.

### Assigning to Components

```matlab
balun = balunMarchand;
balun.Height = 0.0016;
balun.Substrate = sub;
show(balun);
```

Multi-layer substrates are supported by all catalog components that have a `Substrate` or `Height` property (transmission lines, filters, couplers, splitters, etc.).

## Dielectrics in pcbComponent

When building custom structures with `pcbComponent`, dielectrics appear as layers in the `Layers` cell array:

```matlab
pcb = pcbComponent;
substrate = dielectric("RO4730JXR");
substrate.Thickness = 1.52e-3;
ground = traceRectangular(Length=20e-3, Width=10e-3);

pcb.BoardThickness = substrate.Thickness;
pcb.Layers = {signalTrace, substrate, ground};
```

For multi-dielectric pcbComponent stacks (5-layer):

```matlab
sub1 = dielectric(Name="FR4", EpsilonR=4.4, LossTangent=0.02, Thickness=0.8e-3);
sub2 = dielectric(Name="FR4", EpsilonR=4.4, LossTangent=0.02, Thickness=0.8e-3);

pcb.BoardThickness = sub1.Thickness + sub2.Thickness;
pcb.Layers = {topTrace, sub1, groundPlane, sub2, bottomTrace};
```

## Frequenc