One Wire to Rule the Waves – Why a Single Saltwater Radial Supercharges Your Antenna

If you've ever operated portable or maritime, you've probably heard that radials are critical for vertical antennas. But did you know that a single radial—when immersed in salt water—can outperform a whole spiderweb of wires on land? Here's why saltwater changes the game entirely.

Not All Grounds Are Created Equal

On land, your antenna's ground system needs to make up for the lossy nature of soil. Dirt doesn't conduct RF very well. To combat this, hams use many radials—sometimes dozens—to reduce losses and establish a low-resistance return path for RF currents.

But seawater is a different beast. Salt water has a conductivity that's orders of magnitude better than dry soil. It acts as an RF mirror, creating a highly reflective ground plane that enhances radiation efficiency.

The Magic of a Single Immersed Radial

Place a single wire into salt water, and you're tapping into one of the most conductive surfaces on Earth. Here's what happens:

  • Current distribution becomes efficient: The return currents flow naturally into the seawater, with minimal loss.
  • Reduced need for complex radial systems: One well-placed radial in saltwater can do the job of 8, 16, or even 32 radials on land.
  • Cleaner pattern and better signal: With reduced ground losses, more of your RF energy goes into the air—right where you want it.

Rudy Severns, N6LF, Proved It

Rudy Severns has published extensive research showing that just a few elevated radials—or even a single wire into salt water—can rival the performance of a large radial field on land. His measurements demonstrated that over seawater, additional radials offered only minimal improvement (typically less than 0.1 dB), because the salt water already acts as a near-ideal RF ground. His studies remain a reference point for understanding how ground conductivity affects antenna performance.

This Isn’t Magic. It’s Physics.

Saltwater has a very low surface impedance. When your radial touches the sea, you're coupling directly to a massive conductive plane. The low impedance return path allows the antenna system to operate near its theoretical maximum efficiency—even if you're using a short vertical or end-fed wire.

What About a Boat?

If you're operating from a boat, one radial dangling into the sea can make a world of difference—if you maintain a solid connection and proper counterpoise strategy. Boats often float electrically, so your feedline might need a choke or intentional counterpoise to avoid coupling with the whole hull.

Portable? Drag a Wire.

Even when operating from the shore, placing a single insulated wire into the tide can be enough to boost your vertical antenna’s performance. It’s one of the simplest ways to beat the compromise of portable operation.

You don't always need a spiderweb of copper to get out. When salt water is your ground plane, one wire is all it takes to supercharge your signal.

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Written by Joeri Van Dooren, ON6URE – RF, electronics and software engineer, complex platform and antenna designer. Founder of RF.Guru. An expert in active and passive antennas, high-power RF transformers, and custom RF solutions, he has also engineered telecom and broadcast hardware, including set-top boxes, transcoders, and E1/T1 switchboards. His expertise spans high-power RF, embedded systems, digital signal processing, and complex software platforms, driving innovation in both amateur and professional communications industries.