House Noise Isn’t “Vertically Polarized”

You’ve probably heard it on 160/80/40: “That’s house noise. It’s vertically polarized. Use a horizontal antenna and it’ll go away.”

Sometimes a horizontal antenna does sound quieter. But the explanation “house noise is vertical” usually misses the real mechanism. Most of the time you’re not fighting a clean far-field wave with neat polarization. You’re fighting noise coupling: common-mode currents, near-field pickup, and the classic “my feedline/shack wiring has become the antenna.”

The myth (and the tiny bit of truth inside it)

There is one specific situation where “vertical vs horizontal” can matter: when the dominant noise is extended ground-wave from power distribution, a town, or a broad local area, a strong vertical component can show up. A higher horizontal antenna with weak low-angle response can sometimes sound quieter.

(That’s a propagation boundary condition, not a universal rule. It’s also not the same thing as “my LED lamp made my S-meter jump 20 dB.”)

The mistake is using that special case to explain most “house noise.” Inside a home or near a shack, the dominant mechanisms are usually not “far-field polarization” at all.

Why “vertical polarization” is usually the wrong explanation for house noise

Common-mode pickup: your coax becomes the real receiving antenna

If a coax-fed system is unbalanced, current can flow on the outside of the coax shield (common-mode current). At that moment the coax stops behaving like a “boring feedline” and starts behaving like an antenna.

That’s why you can see these symptoms:

• Touching the coax, radio, or a USB cable changes the noise floor
• Noise changes when you reroute the feedline inside the house
• A clamp-on choke near the radio makes the S-meter drop (sometimes a lot)
• Your “antenna” seems to hear the living room better than the band

In this scenario, arguing about the polarization of the radiator is often a distraction, because the feedline + shack wiring geometry is doing much of the receiving.

Near-field coupling: close to the source, the fields are messy

A router wall-wart, LED driver, monitor, solar inverter, Ethernet gear… these aren’t distant transmitters. They’re nearby sources dumping broadband energy into wiring. Close to that wiring you’re often in a near-field environment: capacitive coupling, inductive coupling, and conduction all mix together.

(Near the source, “clean polarization” is not a strong organizing principle. The geometry of wiring and return paths is.)

“Even if it’s on the shield… how does it get into my receiver?”

Because common-mode current on the shield doesn’t always stay politely “outside.” Real coax has transfer impedance and imperfect balance in real stations. Shield current can translate into a differential disturbance at the receiver input, raising the noise floor and filling in what should have been antenna nulls.

Two quick tests that tell you what you’re actually fighting

The breaker test

If it’s safe for your station, run the receiver from a battery (or keep it powered but stable), then switch off circuits one by one. If the noise drops dramatically when a circuit goes dark, you’ve proven the source is mostly local.

The “choke in your hand” test

Snap one or more clamp-on ferrites on the coax right at the radio (or where the feedline enters the house).

• If the noise changes, you’ve got a common-mode coupling problem.
• If nothing changes, either the noise is mainly arriving at the antenna element itself, or your choke is too weak / wrong band / wrong placement.

(Swapping to a dummy load can be misleading because it can completely change the common-mode conditions of the station.)

The fix: make your station stop receiving noise you didn’t ask for

Make the feedpoint “the boundary” with a real common-mode choke

The most effective place to stop feedline pickup is usually the place where it begins: the antenna feedpoint (or the balun/unun output). A proper current choke forces the feedline to be a feedline, not part of the antenna.

If you want a practical, reality-based target for “how much,” use this as a starting point: how much choking you really need for RX and TX.

Don’t rely on folklore coax coils as “broadband chokes”

A big coil of coax can work as a choke on one band and become mediocre (or even counterproductive) on others due to self-resonance and inter-turn capacitance. If your worst noise is on 20–10m, a “160m coax coil” may do almost nothing there.

Choke the other cables attached to your radio

Many stations leak noise through the “side doors,” then that noise finds its way onto the feedline as common-mode. The usual suspects:

• DC power leads
• USB cables to PCs/SDRs
• Ethernet lines (especially with PoE gear nearby)
• Audio/control/rotator lines

This is where shack decoupling and isolation pay off: how antenna-shack decoupling cuts noise and boosts HF reception and why galvanic decoupling at the receiver input improves HF SNR.

Stop accidentally building antennas out of house wiring

You don’t need a perfect installation. You just need to stop creating strong coupling paths. These changes often move the needle immediately:

• Keep coax away from house wiring bundles; cross at right angles instead of running parallel
• Get the feedline down and away from the house quickly (don’t “hug the structure”)
• Avoid long coax runs next to gutters, downspouts, metal window frames, LED wiring, and Ethernet trunks
• Keep noisy devices and their wiring away from the radio, coax, and antenna control lines

Separate “noise coupled” from “noise radiated”

A lot of frustration comes from mixing two different problems:

• Noise radiated ... the antenna is hearing it through space
• Noise coupled ... the station wiring is injecting it into your receiver via common-mode and conduction

If you want a clean way to sort those, this page is the fork in the road: noise coupled vs noise radiated.

So why does “vertical is noisy” feel so true?

Two reasons ... one real, one accidental:

• Sometimes real: extended ground-wave noise can favor vertical pickup in certain conditions, especially on the low bands.
• Often accidental: many vertical installs have weaker common-mode control (counterpoise/return paths “work” for TX, but the feedline and shack wiring still participate).

(When common-mode is present, antenna patterns change, nulls fill in, and the receive noise floor often rises.)

The short version you can tell your friends on 160m

“Sure ... distant ground-wave noise can make verticals sound louder sometimes. But most ‘house noise’ is my station wiring and feedline picking up junk as common-mode and near-field coupling. So I fix it with choking, isolation, and cable management ... not by debating polarization.”

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