What changed
End-fed wires, loops and random wires — edited Aug 31, 2026 by Unknown editor
This is the first recorded version, so every line is shown as added. Note: Imported from content/wiki
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Not every lot supports a center-fed [dipole](/wiki/station/antennas/dipoles). These are the
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alternatives people actually put up, and what each one demands in return.
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## End-fed half-wave (EFHW)
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A half-wave wire fed at one end, where the impedance is very high (2,000–4,000 Ω), through a 49:1
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or 64:1 unun.
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- One support at each end, and the feedpoint can be at the house — the main reason it dominates
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portable operating.
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- A half-wave on 40 m is also a full wave on 20 m and so on, so a single 66-foot wire covers 40,
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20, 15 and 10 m with a small tuner smoothing the edges.
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- The coax braid is part of the antenna's counterpoise. Fit a **common-mode choke** a quarter
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wavelength down the feedline, or you will find [RF in the shack](/wiki/station/rfi-and-noise).
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- Add a short counterpoise (about 0.05 λ) at the transformer; performance improves noticeably.
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## Random wire with a 9:1 unun
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Any convenient length of wire, a 9:1 unun and a tuner.
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- Genuinely multiband, and the least fussy thing to erect.
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- Avoid lengths near a half wave on any band you use, and avoid 32, 64 and 96 feet.
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- Efficiency depends entirely on the radial or counterpoise system; a single wire on the ground is
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the difference between "works" and "works well".
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- Some loss is unavoidable — this is a compromise antenna, and it still makes contacts worldwide.
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## Full-wave loops
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A closed loop, one wavelength around, fed with coax and a 4:1 balun (or open-wire line and a
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tuner).
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- Roughly 1–2 dB of gain over a dipole, and noticeably quieter on receive — the usual reason people
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build them.
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- Horizontal at low height: a superb NVIS antenna for regional
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[emergency nets](/wiki/emergency). Vertical: lower angle and useful for DX.
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- Length in feet ≈ **1005 / frequency in MHz**. Shape matters much less than getting it up.
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## Magnetic loops
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A small tuned loop, typically 3 to 6 feet across, with a high-Q variable capacitor.
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- Works indoors, on a balcony, or on a small patio — often the only option under an
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[HOA](/wiki/station/antennas/hoa-and-stealth).
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- Very narrow bandwidth: retune for every few kHz.
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- Extremely high RF voltages at the capacitor. Do not touch it while transmitting, and keep it out
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of reach.
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- Efficiency falls sharply on the low bands, but 20 m and up can be surprisingly good.
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## Off-center-fed and doublets
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- **OCF (Windom)** — fed about a third of the way along, 4:1 or 6:1 balun, several bands from one
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wire. Common-mode current is its weak point; choke it well.
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- **Doublet** — any length of wire, center-fed with open-wire or ladder line into a balanced tuner.
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Loss stays low even at high SWR, which makes it the most efficient truly multiband antenna, at
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the cost of needing the line to run clear of metal.
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## The common thread
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All of these are compromises against a resonant dipole in the clear. Get the wire high, keep it
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away from gutters and wiring, choke the common-mode current, and none of the compromises will
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matter as much as the height did.