Ground and Elevated Radials Together: Measure the Hybrid System

The original question came from a practical installation: a ground-mounted multiband vertical already had a substantial field of equal-length wires on the soil, so why add raised radials for occasional low-band or contest use? Would the ground field steal current from the raised wires, or would the raised wires bypass ground loss?

The honest answer is more useful than a slogan. Both sets may be connected, and the result may be worthwhile, but “ground radials reduce loss while raised radials provide the clean return” is not a circuit law. Current divides through every path according to its complex impedance and mutual coupling. Adding the raised set changes the antenna; it does not simply bolt an independent improvement onto it.

Why the Two Radial Types Behave Differently

On-ground or shallow-buried radials are strongly coupled to lossy soil. Their currents are loaded and attenuated by soil conductivity, permittivity, moisture, insulation, depth, spacing and length. They spread return current near the base and reduce the field driven through earth, but they do not become isolated free-space quarter-wave wires.

Elevated radials are more visibly part of the radiating structure. Their height, slope, length, symmetry and nearby conductors affect feedpoint impedance, radial-current balance and azimuth pattern. They can reduce the fraction of current dissipated in soil, but a sparse elevated fan can also be more sensitive to asymmetry than a dense on-ground field.

Connecting both creates parallel conductive and displacement-current paths with mutual coupling between them. The ground wires load the near field. The raised wires couple to the radiator, each other, the ground field and the soil. The coax exterior, mast and nearby metal may join the return unless intentionally controlled.

What Rudy Severns Actually Demonstrated

Rudy Severns, N6LF, compared a quarter-wave vertical over 64 on-ground radials with the same vertical over four elevated radials in his 2009 QEX ground-system experiment, Part 3. At 7.2 MHz, with four carefully balanced radials elevated 48 inches, the measured transmission result was within 0.1 dB of the 64-radial on-ground configuration.

That result established that a small, well-controlled elevated system can compete with many ground-surface radials in one geometry. It did not test both systems connected at once, and it did not establish that four casually installed raised wires are universally enough.

Severns made that caveat explicit in his 2012 follow-up on elevated ground systems. Four elevated radials were susceptible to unequal current caused by modest fan asymmetry, nearby conductors and soil variation. He consequently recommended at least 10–12 elevated radials for a more robust real installation.

His multiband radial experiments, Part 6 also resist the internet shortcut that “many short radials always beat fewer long ones.” Specific four-radials-per-band and uniform-length configurations were compared. Sparse sets of only a few long wires performed poorly in that test, while adding wire produced diminishing improvements. The result belongs to the tested bands, soil, radiator and layouts; it is not a universal instruction to shorten every radial.

Will the Ground Radials Steal Current?

“Steal” is the wrong verb. Current divides among all available paths. On one band the elevated fan may carry a large fraction of the deliberate return; on another it may be reactive while the ground field and coax exterior carry more. A current minimum at one point on one wire does not reveal the total current in the system.

Adding ground radials can change the impedance seen by the elevated fan. Adding elevated radials can move the antenna resonance, alter the feedpoint resistance, redistribute coax-exterior current and change pattern. A lower SWR after the change does not prove lower loss; loss itself can make an input look conveniently resistive.

The hybrid is successful only when the measured result matches the actual objective: more radiated field for the same accepted power, better pattern in the required direction, less exterior-feedline current, greater stability with weather, or a useful multiband compromise. One neat dip on an analyser is not enough.

Why the Lower Bands Expose Loss First

When a fixed-height vertical is electrically short on a lower band, its radiation resistance is usually lower and its capacitive reactance must be compensated. Ground, conductor and matching loss can then consume a larger fraction of accepted power. Improving the return system may matter more—but the result still depends on how the complete antenna is loaded and matched.

A raised wire that produces a new matching dip is not automatically a lower-loss radial. It may have introduced a coupled resonance, shifted current onto the coax or changed the matching network’s transformation. Measure current, accepted power and field before assigning the cause.

A Multiband Elevated Fan Is Not a Set of Independent Wires

It is tempting to label one raised wire “40 metres,” another “30 metres” and assume each sleeps on the other bands. It does not. Every wire has a complex impedance and couples to every other conductor. A wire near quarter-wave on one band may be a low-impedance return there, while becoming reactive or supporting a different current distribution elsewhere.

For a multiband hybrid, equal spacing and repeatable height matter. So do the number of wires, their common connection, their angles relative to the radiator and whether their ends approach fences, buildings, wet vegetation or people. If the site cannot keep a sparse elevated fan symmetric, a larger fan or the existing on-ground system may be the more predictable engineering choice.

The Choke Sets a Boundary; It Does Not Supply a Missing Return

A common-mode choke raises the impedance of the coax-exterior path at the point where it is installed. That can make current redistribute into the intentional radial systems. It cannot guarantee equal current in elevated wires, compensate for a lossy ground field or make the coax disappear electromagnetically.

Use a feedpoint choke as a deliberate starting boundary, then map exterior-shield current at several positions and on every operating band. If substantial current remains, inspect the radial impedance and the complete installation before adding chokes by habit. A standing-wave minimum under one clamp position can hide larger current elsewhere.

How to Test a Hybrid Radial System Fairly

The useful experiment compares three configurations rather than comparing memories from different weekends:

For every configuration:

• keep radiator height, matching hardware, feedline route and measurement reference plane unchanged;
• record complex feedpoint impedance over the full band, not only minimum SWR;
• measure current in each elevated radial and sample representative ground wires;
• map coax-exterior current at repeatable positions;
• record forward, reflected and accepted power at declared reference planes;
• compare remote field or wanted-signal SNR with A/B/B/A or simultaneous channels;
• restore the first configuration and confirm the baseline; and
• repeat after soil moisture or weather changes before claiming stability.

If the radiator must be retuned for each radial configuration, record both the raw and retuned result. Retuning is a valid station decision, but it changes more than the radial system and must not be hidden inside the comparison.

Safety Can Decide Against the Elevated Set

A removable “contest mode” set is worthwhile only if the site can deploy it symmetrically and safely. Wet foliage, fences, guy wires and temporary supports can detune the fan or create touch points. A permanent ground field may lose a fraction of a decibel yet still win the whole engineering decision through repeatability, access control and maintenance.

When the Hybrid Earns Its Place

A hybrid radial system makes sense when the permanent ground field provides a reliable everyday baseline and a safely deployed elevated fan produces a repeatable improvement in a defined metric. It does not make sense merely because one system is called broadband and the other low loss.

The reader’s instinct was right: ask whether the two systems interfere. They do interact. That interaction may be useful, neutral or harmful depending on band and site. Measuring ground-only, elevated-only and combined configurations turns the question from folklore into engineering.

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