The EFHW Below 20 Meters: Popular, Easy, and Mostly Useless

The End-Fed Half-Wave (EFHW) antenna is widely promoted as a multiband miracle. But when you strip away the marketing, only one type of EFHW truly holds up on bands than higher then 20 meters:

The dual-band half-wave/full-wave EFHW.

Forget about gimmicks, traps, or capacitors. If you're not using a real half-wave or full-wave radiator, you're just playing impedance games.

What Actually Works on Bands Longer Than 20 m

160/80 m EFHW (Full-wave on 80m, Half-wave on 160m)

  • A ~80.4 m radiator in inverted-L layout provides half-wave resonance on 160m and full-wave on 80m.
  • Requires a 68:1 transformer for proper impedance transformation.
  • Needs a 1:1 current choke at 0.05 λ on the coax.
  • Also requires a high-impedance path to ground to stabilize the system due to the long wire and common-mode coupling. See: Why EFHW antennas are inherently unstable, especially on low bands.

80/40 m EFHW (Full-wave on 40m, Half-wave on 80m)

40/20 m EFHW (Full-wave on 20m, Half-wave on 40m)

  • A ~20.1 m radiator is a classic dual-band EFHW.
  • Uses a standard 49:1 transformer and a 1:1 current choke at 0.05 λ.
  • Predictable low-angle radiation on 40m and multi-lobe pattern on 20m.

20 m Monoband EFHW (Half-wave Only)

  • A ~10.1 m radiator acts as a clean half-wave on 20m.
  • Uses a 49:1 transformer and a 1:1 choke at 0.05 λ.
  • Simple, efficient, and free of matching gimmicks.

Why Other Multiband EFHWs Fail on Bands Lower Than 20m (17–10m)

Many commercial EFHWs add parallel capacitors or rely on transformer reactance to simulate resonance on higher bands.

These are not true resonances — they are impedance artifacts, often resulting in extremely poor efficiency.

Yes, you will make contacts. Any piece of wire in the air will make some kind of contact. But that's not the point. The question is: how much power are you actually radiating?

If you’re tuning an antenna that’s supposed to be a half-wave into resonance, something is inherently wrong. You're no longer working with a resonant radiator — you're patching a mismatch with a tank circuit.

At that point, you’re far better off with a properly designed 1/4-wave vertical or a 5/8-wave vertical, which offers real current maxima, controlled radiation, and far better efficiency.

The Bottom Line

Stick with EFHWs in dual-band formation between 160–20 m where real λ/2 and λ resonances exist:

  • Use 160/80 with a 68:1 (inverted L) + 1:1 choke + high-Z bleed
  • Use 80/40 with a 70:1 (inverted L) + 1:1 choke + high-Z bleed
  • Use 40/20 or monoband 20 m with a 49:1 + 1:1 choke

For 20–10 m, skip the EFHW mythology. Use an EFOC8 or any antenna that will actually radiate.

Pretty SWR doesn't mean real resonance.
Feed a resonant wire — not a reactive trick.

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Written by Joeri Van Dooren, ON6URE – RF, electronics and software engineer, complex platform and antenna designer. Founder of RF.Guru. An expert in active and passive antennas, high-power RF transformers, and custom RF solutions, he has also engineered telecom and broadcast hardware, including set-top boxes, transcoders, and E1/T1 switchboards. His expertise spans high-power RF, embedded systems, digital signal processing, and complex software platforms, driving innovation in both amateur and professional communications industries.