End‑Fed Antennas Explained

What Is an End-Fed Antenna?

Unlike dipoles, which are fed at the center, end-fed antennas are connected at one end. This makes them attractive for small gardens, stealth installs, and portable operations—since only one support point is required. But “end-fed” is not one thing; there are three main flavors: EFHW, EFOC, and EFLW.

End-Fed Half-Wave (EFHW)

The EFHW resonates at a half wavelength on its fundamental frequency. Because of harmonic resonance, it also works on odd/even multiples (e.g., an 80m EFHW often covers 80/40/20/15/10m). The impedance at the feedpoint is very high (2–3 kΩ), requiring a broadband step-down transformer (typically 49:1 or 64:1).

• ✔ Simple to install and covers multiple bands
• ✔ Efficient on its fundamental and harmonics
• ⚠️ Transformer losses increase at high power
• ⚠️ Feedpoint impedance is highly environment-sensitive on low bands

Key nuance: standard 49:1 EFHWs are unstable on lower bands due to soil and height variations. However, in purpose-built Inverted-L designs with higher ratio transformers (68:1–70:1), stability improves dramatically—showing that transformer design and geometry matter as much as the wire itself.

End-Fed Off-Center (EFOC)

The EFOC is a hybrid between a dipole and EFHW. The wire is tapped off-center (often around 20–25% from one end), yielding a more manageable impedance (~200 Ω). With a 4:1 unun, the feedpoint becomes much more tuner-friendly.

• ✔ Broader and more stable band coverage than EFHW
• ✔ Lower transformer ratios reduce ferrite heating
• ✔ Works well with modest tuners
• ⚠️ Still requires a counterpoise or choke for stability

The EFOC often proves the most practical “install-and-forget” multiband option for field operators and fixed stations alike.

End-Fed Long Wire (EFLW)

The EFLW is not resonant on any specific band. It is simply a long wire (typically 16–50 m) fed through a 9:1 unun and a wide-range tuner. Performance depends strongly on wire length, height, and grounding.

• ✔ Extremely flexible layout—L, sloper, zig-zag, etc.
• ✔ One antenna can cover many bands with a good tuner
• ⚠️ Efficiency varies dramatically by band and length
• ⚠️ Requires strong common-mode suppression to avoid RF feedback

EFLWs are great for portable “catch-all” use, but not ideal for high-efficiency operation.

Why We Do Not Like the “Wideband EFHW”

Some commercial EFHWs are marketed as “wideband” solutions, claiming low SWR across HF without a tuner. In reality:

• The flat SWR curve often comes from lossy ferrites or resistive elements inside the transformer.
• This “absorbs” mismatch rather than transferring power to the antenna.
• Efficiency can be dramatically reduced—sometimes more than half the RF power is lost as heat.

In other words, a “wideband EFHW” is often just a disguised dummy load with some radiation. We strongly advise purpose-built EFHWs with efficient transformers over any lossy “broadband” trickery.

Choosing Between EFHW, EFOC, and EFLW

The right end-fed antenna depends on your goals and space:

• EFHW: Efficient for harmonics of its fundamental—good if you want classic multiband coverage with some compromises.
• EFOC: Balanced compromise between efficiency and tuner-friendliness—our preferred option for most multiband setups.
• EFLW: Maximum flexibility—excellent for portable and “one-wire covers all” operations, with efficiency tradeoffs.

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