EFHW vs. EFOC: Two Voltage-Driven Antennas, Two Smart Solutions
Updated August 21, 2025
End-Fed Half-Wave (EFHW) and End-Fed Off-Center (EFOC) antennas are both voltage-fed wire antennas. While they may look similar — both fed at the end and both requiring impedance transformers — their current distribution, height sensitivity, and operating behavior reveal clear differences.
Rather than one being “better,” they represent different solutions for different environments.
EFHW: Precision Tool for Serious DX
The EFHW is resonant and excels when installed at proper height. At resonance, it has a strong current maximum mid-span and very high voltage at the ends. This allows efficient radiation on its fundamental and second harmonic, making it an effective dual-band solution (e.g., 40m/20m, 80m/40m).
Most effective when:
- Mounted at least ½ wavelength above ground (horizontal)
- Mounted 3–7 m+ for sloped or vertical (higher = lower takeoff)
- You want sharp low-angle radiation for DX
Limitation: too low an install hurts efficiency, especially on harmonics.
EFHW Advantages
- Clean low-angle DX radiation when high
- Dual-band efficiency (½λ + full-wave harmonic)
- Great for portable and stealth DX — if you have height
EFHW Limitations
- Needs height for proper efficiency
- High-voltage feedpoint stresses transformer/insulation
- More prone to coupling with surroundings
EFOC: The Forgiving All-Rounder
The EFOC is a multiband, general-purpose tool. Using a 4:1 UNUN, the off-center feedpoint shifts the current maximum closer to the transformer, lowering Z to ~150–600 Ω. This makes it more tolerant of placement.
More forgiving when:
- Mounted at 5–8 m height
- Installed on or near rooftops
- Used as sloper or inverted-L
Not a DX beast like a high EFHW, but excellent for everyday use, especially with choke and counterpoise.
EFOC Advantages
- Tolerant of lower heights
- Easier impedance match (lower feedpoint Z)
- Stable multiband compromise
EFOC Limitations
- Less ideal for low-angle DX
- Slightly less efficient due to current asymmetry
- Sometimes needs counterpoise/radiator tuning
So Which Should You Choose?
| Use Case | Best Choice |
|---|---|
| High DX performance, elevated installation (10m+) | EFHW (mono/dual band) |
| Compact rooftop or balcony | EFOC |
| Efficient dual-band pairing (40/20 or 80/40) | EFHW |
| Ease of tuning, forgiving placement | EFOC |
| Reliable portable multiband | EFOC |
Bottom Line: Know Your Environment
These antennas are complementary, not competitors. EFHW is a precision DX tool if you have space and height. EFOC is a forgiving multiband option when space, height, or simplicity matter more.
Mini-FAQ
- Is EFHW better than EFOC? — Not better, just different. EFHW is more efficient at height, EFOC is more forgiving at modest installs.
- Why do EFHWs stress transformers? — The feedpoint is at a voltage maximum, requiring high turns ratio and insulation.
- Does EFOC need a counterpoise? — A short counterpoise or coax shield reference improves stability, but it is less critical than with EFHWs.
- Can clamp meters distinguish current types? — No. They only detect net RF current on the shield — regardless of mode.
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