Ideal thickness for copper feed for cantenna at 1420 Mhz

The ideal thickness (gauge) of copper wire for the feed in a cantenna (typically for Wi-Fi at 2.4 GHz) depends on both practical and theoretical factors, mainly skin depth, mechanical stability, and ease of soldering.

Recommended Copper Wire Thickness

• Gauge: 14 to 12 AWG (about 1.6–2.0 mm diameter).
• Why:
  • At 2.4 GHz, the skin depth in copper is about 1.3 microns, so RF current only flows in the outer layer of the wire. You don’t need thick wire for conductivity, but…
  • Mechanical rigidity matters. Thinner wires are floppy and harder to keep in place inside the can.
  • Soldering and securing the wire to an N-type connector or similar is easier with 14–12 AWG.

Key Tip

• The length of the feed probe is far more critical than thickness — it should be about ¼ wavelength in the can’s dielectric (usually ~31 mm in air for 2.4 GHz, adjust if plastic or other material inside).

Recommended Copper Wire Thickness for 1420 MHz

For 1.42 GHz (the hydrogen line), the optimal copper wire thickness for the cantenna feed changes slightly to accommodate the lower frequency and longer wavelength.

• Gauge: 12 to 10 AWG (about 2.0–2.6 mm diameter)
• Why:
  • Still well within the RF skin depth (~1.8 µm at 1.4 GHz), so thick wire isn’t required for conductivity.
  • But mechanically, you’ll benefit from a sturdier feed element, especially if you’re mounting it through an N-type connector or similar.
  • Thicker wire also better matches the wave impedance and ensures minimal signal loss at the connection.

Feed Probe Length (Very Important)

• In air: ~52.8 mm (¼ wavelength at 1420 MHz)
• In a can (depending on dielectric): Reduce by ~5–10% if the can interior has dielectric material.
• Start with 50–53 mm and test tuning using an SWR meter or network analyzer, if available.