Your EFHW Isn’t Noisy — Your Feedline Is

End-Fed Half-Wave antennas (EFHWs) have a reputation: “They’re noisier than a dipole.” Sometimes it seems true in the shack: you swap from a center-fed dipole to an EFHW and the S-meter jumps, the waterfall gets hairier, and the band sounds more aggressive.

Here’s the key point: an antenna doesn’t generate noise. It couples to noise fields that already exist. So when people say “EFHWs are noisy,” what they’re usually seeing is extra coupling to local noise because the return path (and therefore common-mode current on the feedline) isn’t controlled.

(Practical summary) A well-choked EFHW with a defined return path can be just as “quiet” as a well-fed dipole in the same environment.

What hams mean by “noisy” on HF

On HF, what you hear is usually a mix of:

• Atmospheric noise (storms, static, distant weather)
• Man-made noise (switch-mode power supplies, LED lighting, solar inverters, Ethernet gear, etc.)
• Receiver/system noise (often not the limit on HF unless the antenna is tiny or very inefficient)

In many modern neighborhoods, local man-made noise dominates. Small changes in what part of your station “acts like an antenna” can change the noise floor dramatically. That’s where the EFHW myth comes from.

The real culprit: uncontrolled common-mode current

Differential mode vs common mode (plain language)

A coax feedline is supposed to carry RF as differential-mode current: signal flows as a pair (center conductor vs the inside of the shield), and the fields mostly stay inside the coax.

But if the antenna system is unbalanced (or becomes unbalanced because of surroundings), you can also get common-mode (CM) current on the outside of the coax shield.

Why EFHWs often get blamed

1) The return path is easy to “accidentally” put on the coax

An EFHW is end-fed, so the antenna system still needs a return path. Physics demands a loop: current out must come back. If you don’t provide a defined counterpoise/return, the system will “find” one:

• the coax shield
• station ground wiring
• your rig, mic, and connected cabling
• house wiring nearby (through capacitance)

That invisible/accidental return path is usually what makes an EFHW seem noisier.

2) EFHW feedpoints are often close to the house

Many EFHW installs place the transformer where it’s convenient (window, balcony, gutter line, wall entry). If the coax shield is carrying CM current, you just created a very effective “noise probe” right next to the worst offenders: switching supplies, LED drivers, routers, and house wiring.

3) A dipole isn’t magically immune either

A dipole is balanced, but coax is unbalanced. If you feed a dipole with coax without effective current choking (and decent routing), the dipole system can also develop common-mode current and “import” noise on the feedline.

The fix: control the return path and isolate the feedline

To bust the myth in practice, you do two things:

• Provide (or control) the return path for the end-fed system
• Stop the feedline from becoming that return path beyond the point you choose

Step 1 — Use a real common-mode choke

A common-mode choke (line isolator / current balun behavior) raises impedance to current on the outside of the coax shield. That helps keep the shield from becoming part of the antenna system near the shack.

Practical placement: many stations benefit from one choke near the feedpoint (or right after the intentional counterpoise section), and sometimes a second choke at the shack entry in noisy homes.

Step 2 — Give the EFHW a defined counterpoise (on the antenna side of the choke)

Here’s the “gotcha”: if you choke the coax hard right at the transformer and provide no counterpoise, you may reduce the only return path the system was using. Then the antenna will either underperform or force return current through stray capacitances in unpredictable ways.

The goal is simple: let the return path exist where you want it (outside, on the antenna side), and keep it out of the shack.

• Counterpoise wire on the transformer ground/return side
• A deliberate short coax “counterpoise section” between transformer and choke
• Short radials if the feedpoint is at ground level (portable setups often benefit)

A simple mental model

Think of your EFHW install as two “zones”:

Antenna system (allowed to receive/radiate)

• EFHW wire
• transformer/unun
• your chosen counterpoise (wire/radials/short coax section)
• short feedpoint connections

Station system (should NOT be part of the antenna)

• long coax run into the house
• radio, power supply, USB/audio wiring, computer, network cabling

The myth happens when those two blur together. A good choke is what draws the line.

“So will a properly built EFHW be as quiet as a dipole?”

In most typical HF stations: yes, it can be. Once you prevent the feedline shield from acting like a random receive antenna near the shack, and you put the EFHW’s return current where it belongs (counterpoise / controlled section), the “extra EFHW noise” often disappears.

Any remaining differences are usually explained by installation variables, not the feed method:

• Pattern differences (what directions/angles the antenna favors)
• Polarization differences (local E-field noise can couple more strongly in some geometries)
• Placement differences (distance to house wiring, gutters, metalwork, and electronics)

Practical “Quiet EFHW” checklist

• Use an effective common-mode choke near the feedpoint (or right after the intentional counterpoise section)
• Add a defined counterpoise so return current is controlled and repeatable
• Route the coax away at a right angle when possible (avoid taping it alongside the radiator for long runs)
• Move the feedpoint away from the noisiest spot (even a few meters can matter)
• Don’t chase “magic coax lengths” — routing and surroundings dominate

How to myth-bust it in your own station

• Compare EFHW and dipole at similar height and distance from the house, same band, same receiver settings (same bandwidth, preamp off)
• Add/adjust choke + counterpoise on the EFHW
• Watch whether the noise floor drops without a proportional drop in desired signals
• If a choke reduces noise, that’s the giveaway: the feedline was acting like a noise antenna

Bottom line

The better way to phrase the truth is this:

EFHWs aren’t inherently noisier than dipoles.
Uncontrolled return currents and feedline common-mode pickup are noisier.

If an EFHW “sounds noisy,” it’s usually because the coax shield (and sometimes the whole station) has become part of the antenna system—right where all the man-made noise lives. Add a proper choke and a defined counterpoise, and an EFHW can become just as “quiet” as a properly fed dipole, with remaining differences explained by pattern, polarization, and placement.

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