6 Feet (≈ 1.8 Meters) of Radials Will Fix Everything? — What N6LF Actually Found
Updated Nov 2025 — Technical review based on Rudy Severns (N6LF) field data and measurement reports.
Some online posts claim that adding just six feet (≈ 1.8 m) of dense radials around a vertical antenna can outperform a “Faraday cloth” by 10×. That sounds convenient—but it doesn’t match what decades of field data actually show. Here’s what Rudy Severns (N6LF) and other measurement-driven engineers found about ground systems that really work.
The science behind dense near-base coverage
Rudy’s HF experiments prove most ground loss happens very close to the base—within about ⅛ wavelength (0.125 λ). That region must have dense radial coverage, but its size scales with band—not a fixed 6 ft (1.8 m):
| Band | Approx. Radius (0.125 λ) |
|---|---|
| 80 m | ≈ 35 ft (10.7 m) |
| 40 m | ≈ 17.6 ft (5.4 m) |
| 30 m | ≈ 12.3 ft (3.7 m) |
| 20 m | ≈ 8.8 ft (2.7 m) |
| 17 m | ≈ 6.8 ft (2.1 m) |
| 15 m | ≈ 5.9 ft (1.8 m) |
| 10 m | ≈ 4.4 ft (1.3 m) |
“6 ft (1.8 m)” corresponds roughly to 17 m band only. For lower bands, the critical zone is much larger, and shrinking it causes steep efficiency losses.
More short radials > fewer long ones — to a limit
For a fixed total wire length, more shorter radials reduce ground loss more effectively than a few long ones, up to an optimum. N6LF and K3LC found that 24–32 radials on 40 m and 16–32 on 20 m approach the point of diminishing returns.
Why a “Faraday cloth” is not a ground system
Small conductive mats or “magic carpets” offer only localized shielding. Rudy’s Excessive Loss in Sparse Radial Screens paper showed that limited screens or few short wires still cause major loss. A mesh under the feedpoint helps only as a supplement—the real current returns through proper radials.
Elevated tuned radials — the efficient alternative
Four λ/4 elevated radials ≈ 32–65 ft (10–20 m) long and ≈ 48 in (1.2 m) above ground measure within 0.2 dB of a 64-radial ground field. Two or three can work temporarily for portable use, but four or more are recommended for consistent results and symmetry. Always add a good feedpoint choke to suppress common-mode currents.
Practical band-by-band recipes (imperial + metric)
- 20–10 m (Portable / POTA): 16–32 radials ≈ 6–10 ft (2–3 m) each, evenly spaced. Optional mesh at the base adds stability.
- 40 m: 24–32 radials ≈ 30–40 ft (9–12 m). If shorter, add more to compensate for loss.
- 80 m: Dense zone ≈ 35 ft (10.7 m) radius. Small mats alone are insufficient without real radials.
- Elevated systems: Four or more tuned λ/4 radials ≈ 32–65 ft (10–20 m) at ≥ 0.05 λ height match big ground fields in efficiency.
Summary — what N6LF’s data really show
- Dense coverage near the feedpoint matters, but its radius scales with band (≈ 0.125 λ), not a fixed 6 ft (1.8 m).
- Small screens are not substitutes for radials; they only reduce localized loss right at the base.
- Short radials in quantity offer the best return on wire until the efficiency curve flattens.
- Elevated radials — four or more tuned and symmetrical — rival large ground fields with less wire and space.
Bottom line
Efficient vertical systems depend on a conductive region extending about ⅛ wavelength from the base. “Six feet (1.8 m)” is not a universal magic radius — it only applies to the 17 m band. Design your radial field to scale with frequency: screens help, but radials do the real work.
Mini-FAQ
- Do radials need to be buried? — No. Laying them on the ground works almost as well; burial mainly protects them mechanically.
- Can I mix radial lengths? — Yes. Mixing ≈ 10–20 ft (3–6 m) lengths helps smooth impedance across bands.
- What wire type is best? — Copper or tinned stranded wire ≥ 0.8 mm² (≈ 18 AWG). Bare wire improves soil contact.
- Does soil type matter? — Yes. Dry sandy soil needs more radials than moist clay or coastal loam for the same efficiency.
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