Materials Library
Comprehensive reference for antenna construction materials including conductors, capacitors, and transmission lines. All data sourced from manufacturer specifications and engineering references.
Conductor Materials
Electrical and physical properties of common conductor materials used in antenna construction. Resistivity values at 20°C.
| Material | Resistivity (Ω⋅m) | Rel. Permeability | Density (g/cm³) | Thermal Exp. (10⁻⁶/K) | Recommended Use |
|---|---|---|---|---|---|
| Copper Pure copper (99.9% Cu) - Standard for antenna construction | 1.68e-8 | 0.999994 | 8960.00 | 16.5 | Most common conductor for antennas. Excellent conductivity and corrosion resistance when protected. |
| Aluminum Pure aluminum (99.5% Al) - Lightweight alternative | 2.82e-8 | 1.000022 | 2700.00 | 23.1 | About 60% as conductive as copper but much lighter. Good for large loops. Forms protective oxide layer. |
| Brass Brass alloy (Cu-Zn) - Good for capacitor plates | 6.40e-8 | 1 | 8500.00 | 20.0 | Less conductive than copper but easier to machine. Often used for tuning capacitor plates. |
| Steel Wire Galvanized or stainless steel - Budget option | 1.43e-7 | 100 | 7850.00 | 11.0 | Poor conductor due to high resistivity and magnetic properties. Not recommended for transmitting antennas. |
| Custom Material Define your own material properties | 2.00e-8 | 1 | 8000.00 | 17.0 | For experimental or special materials not listed above. |
Material Selection Guide
Copper: Best overall choice for most antennas. Excellent conductivity, readily available, easy to work with. Recommended for loops, dipoles, and verticals.
Aluminum: Lightweight alternative to copper. 60% the conductivity but 1/3 the weight. Ideal for large antennas where weight matters. Requires special oxidation prevention.
Brass: Good conductivity with excellent corrosion resistance. Popular for marine and outdoor installations. More expensive than copper.
Steel: Poor conductor but mechanically strong. Used only where structural strength is critical. Not recommended for RF elements.
Skin Depth vs. Frequency
At RF frequencies, current flows primarily in the outer skin of conductors. This affects effective resistance.
| Frequency | Copper (μm) | Aluminum (μm) | Brass (μm) | Implication |
|---|---|---|---|---|
| 1.8 MHz (160m) | 48.8 | 63.4 | 55.2 | Thick tubing beneficial |
| 7 MHz (40m) | 24.7 | 32.1 | 27.9 | Wall thickness critical |
| 14 MHz (20m) | 17.5 | 22.7 | 19.7 | Plating effective |
| 28 MHz (10m) | 12.4 | 16.1 | 14.0 | Thin walls acceptable |
| 146 MHz (2m) | 5.4 | 7.0 | 6.1 | Very thin conductor OK |
Skin depth (δ) is the depth where current density falls to 37% of surface value. For efficient RF conduction, conductor radius should be at least 2-3× skin depth.
Data Sources & References
Conductor Data: CRC Handbook of Chemistry and Physics, 103rd Edition. Resistivity values at 20°C (68°F), 1 atmosphere pressure.
Skin Depth Calculations: Calculated using formula δ = √(ρ / (πfμ₀μᵣ)) where ρ = resistivity, f = frequency, μ₀ = vacuum permeability, μᵣ = relative permeability.
Capacitor Specifications: Manufacturer datasheets from Cardwell Condenser, Jennings Technology, and Hammarlund.
Coax Data: Times Microwave LMR Series specifications, Belden Cable datasheets. Loss figures measured at 25°C.
Additional References: ARRL Handbook for Radio Communications, IEEE Standard for Coaxial Cable Specifications, Vintage Radio repair guides.
Using This Data
This materials library is integrated into HamCalc's calculators. When you select a conductor type or capacitor in the calculator, these specifications are automatically used in the calculations.