Myth Debunked: Loops Are Not Automatically Self-Balancing
In ham radio circles, one recurring claim is that “loops adopt and keep their perfect symmetry, even in disturbed environments.” This idea gets repeated often, sometimes with references to IEEE or IET papers. The problem: those papers deal with special engineered loop structures, not the resonant multiband HF loops you put up in your garden.
Where the Confusion Starts
There are academic publications about self-balanced wideband folded loops or self-balancing small loops. In those designs, geometry and feed arrangement are engineered to suppress common-mode currents on ground planes in very narrow conditions. These are usually:
- Electrically small loops (much less than λ/4 in circumference)
- PCB-style or folded structures
- Designed for specific band-limited applications (e.g. RFID, IoT, EMC test setups)
Projecting those results onto full-size HF loops (80–10 m) is simply wrong. A backyard delta or quad loop is not inherently “self-balanced” just because it’s a loop.
Reality Check: HF Loops Still Need Balancing
A resonant HF loop will radiate nicely when fed symmetrically, but if you connect coax directly—or operate in a distorted environment—the coax becomes part of the antenna. That means:
- Common-mode currents on the feedline
- Extra household noise picked up on receive
- Pattern distortion, especially on the low bands
(In other words: a loop is not a magical CMC shield. Without a proper choke, it misbehaves like any other unbalanced feed.)
Balanced Feeders vs. Symmetrical Tuners
Feeding loops with ladder line and a truly symmetrical ATU (like the LazTuner 4 kW or 10 kW) is a neat solution—but it’s not the only valid approach. A balanced antenna with ladder line, a good 1:1 choke, and a conventional tuner works perfectly well. The key factor is how effectively common-mode current is suppressed, not the marketing term “true symmetry.”
| Myth | Fact |
|---|---|
| Loops always stay perfectly symmetric, even in disturbed environments. | Symmetry only holds in free-space with a balanced feed. In real installations, coax or nearby objects break it. |
| Loops don’t need baluns because they are “self-balancing.” | All practical HF loops fed with coax need a choke or balun to block common-mode currents. |
| Scientific papers prove ham loops are self-balancing. | The papers describe engineered, electrically small or folded loops, not resonant HF loops used by hams. |
Takeaway
The “loops always stay symmetric” statement is a half-truth. Yes, loops are geometrically balanced—but only in free-space and with symmetric feeding. In the real world, they behave like any other antenna: imbalance creeps in, and only proper choking/balancing fixes it. Don’t let scientific papers about niche loop structures be misapplied to HF ham antennas.
Mini-FAQ
- Do all loops need a balun? — Yes. Unless you use perfectly symmetric ladder line with a true balanced tuner, you need a choke or balun.
- Are “self-balancing loops” real? — Yes, but only in engineered, electrically small designs (not typical HF resonant loops).
- What’s the best choke for loops? — For 160–10 m coverage, stacked FT-240-31 cores with 7–10 turns of coax are the proven choice.
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