Elevated vs On-Ground Radials — Which Really Works Better?

A science-based look at what Rudy Severns (N6LF) and other researchers actually found.

TL;DR

• Both systems can be highly efficient. Under ideal conditions, a vertical with four tuned, elevated ¼-wave radials can match a ground-mounted vertical with dozens of on-ground radials — but it’s very sensitive to asymmetry and nearby conductors. Rudy Severns’ later guidance is to use at least 10–12 elevated radials to make performance robust.
• On-ground/buried radials are forgiving. Classic broadcast-band and ham research shows big gains as you add radials, with diminishing returns beyond a few dozen; many stations aim for 16–60+ depending on goals and space. Radials lying on or in the soil do not need to be resonant.

Why Radials Matter

A vertical’s “other half” is the displacement current returning through the ground. The job of the radial system — elevated or on/in the soil — is to provide a low-loss return path so less of your transmitter power heats the dirt and more is radiated.

What the Experiments and Models Actually Show

N6LF — Careful Experiments + NEC4 Modeling

• Elevated radials can be extremely efficient — but touchy. Four elevated ¼-wave radials can equal a 60-radial ground mat when geometry is perfect. Real-world asymmetry or nearby conductors often upset balance. Rudy’s practical guidance: use ≥ 10–12 elevated radials.
• How high and how tuned? Raising radials even modestly reduces loss. Elevated systems act like coupled resonators: trim and keep them symmetric. Measured gain rises with height, but current sharing becomes unequal across the band.
• On-ground pragmatics. Using NEC-4D, Rudy showed more, shorter on-ground radials outperform fewer, longer ones for the same wire budget. Beyond ≈ 0.15 λ the far ends carry little current. About 32 radials often minimize loss for a fixed total length.

Modeling caution: NEC-2 does not model near-earth coupling accurately; N6LF used NEC-4D for valid HF vertical results.

Brown, Lewis & Epstein (1937)

Their 3 MHz field-strength data proved that 60–120 on-ground or buried ¼-wave radials approach the “perfect ground” limit, with diminishing returns beyond that. Buried radials lose resonance, so precise length isn’t critical.

Jerry Sevick (W2FMI)

At 40 m he measured input resistance approaching ≈ 35 Ω with ≈ 115 radials — near loss-free behavior. At ≈ 16 radials, 0.2 λ vs 0.4 λ made almost no difference — count and coverage matter more than resonance.

Al Christman (K3LC) and Colleagues

Modeling and field data show that for a fixed wire budget, more shorter radials often win. Properly tuned elevated systems can rival large ground mats — but require symmetry and height. U.S. Navy research (Dawson & Lockwood) likewise found efficiency drops predictably as radial count is reduced.

Elevated vs On-Ground — When Each Wins

Elevated Radials — When They Shine

• Space-efficient efficiency. Ten to twelve ¼-wave radials, symmetric and clear of metal, can deliver top efficiency with far less wire — ideal for small lots.
• Cleaner loss budget. Lifting the return conductors cuts soil loss and boosts measured gain.

Caveat: Four-radial systems are fragile — small mismatches or nearby objects quickly unbalance them. Rudy’s later recommendation ≥ 10–12 radials is the safe zone.

On-Ground / Buried Radials — When They Win

• Robustness and simplicity. Forgiving of errors and clutter, and non-resonant. Start with 16–32 radials; 60+ approaches broadcast-grade efficiency.
• Wire-budget optimization. For limited wire, prioritize count and coverage; beyond ≈ 0.15 λ length, benefit flattens.

Practical Build Recipes

“Reliable Elevated” (Example 40 m Vertical)

• Radials: 10–12 × ¼-wave, equal height, symmetric fan; trim for resonance after feedline attached.
• Height: Raise several meters; keep away from metal and uneven ground.
• Feed: Add a 1:1 choke at base so feedline doesn’t act as a radial; verify current balance if possible.

“Forgiving Ground Mat” (80 / 40 m)

• Start with 16–32 radials on grass or shallow-buried (~0.1–0.2 λ each).
• No need for resonance; coverage near the base matters most.
• With limited wire, choose more shorter radials; ≈ 32 often optimum for a fixed wire budget.

Hybrid Fix for Aging Grounds

Adding a few elevated radials above a deteriorated buried system can recover efficiency — a proven broadcast-engineering trick.

Myths to Retire

• “Every radial must be ¼-wave.” Only for elevated systems. On-ground radials are non-resonant.
• “Four elevated radials always beat 60 ground radials.” True only for perfect geometry; in practice use ≥ 10–12 for stability.
• “Longer is always better.” Beyond ≈ 0.15 λ with few radials, returns flatten. Count beats length.

The Bottom Line

• If you can maintain a balanced elevated fan (≥ 10–12 radials), you get broadcast-grade efficiency with minimal wire — the elegant small-lot solution.
• If you want “set and forget” robustness, lay down as many on-ground radials as space and patience allow — 16–32 is solid; 60+ is superb.

Sources & Further Reading

• Rudy Severns (N6LF) — A Closer Look at Vertical Antennas with Elevated Ground Systems
• Rudy Severns (N6LF) — Vertical Antenna Ground Systems at HF (Dayton Forum Notes)
• Brown, Lewis & Epstein (1937) — Ground Systems as a Factor in Antenna Efficiency
• Jerry Sevick (W2FMI) — The Ground-Mounted Short Vertical (QST 1973)
• Al Christman (K3LC) — Maximum-Gain Radial Ground Systems for Vertical Antennas (NCJ 2004)
• Dawson & Lockwood — Revisiting Medium-Wave Ground-System Requirements (IEEE 2008)

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