These Two Inverted L End-Fed Antennas Will Crush DX on 160/80m and 80/40m

When chasing performance on the low bands, two specific end-fed inverted L designs stand out:

  • 160/80m with a 68:1 transformer
  • 80/40m with a 70:1 transformer

Both are carefully engineered to provide efficient, low-angle DX radiation from a single-wire antenna with a single feedpoint.

Let’s break down both antennas—what they are, why they work, and why they outperform many alternatives in real-world DX conditions.

160/80m End-Fed Inverted L with 68:1 Transformer

Geometry & Design

  • Wire length: ~79–81 meters
  • Feedpoint height: Minimum 1 m, ideally 2–5 m
  • Vertical section: At least 15 meters tall, remainder horizontal or sloped
  • Matching: 68:1 transformer
  • Grounding: Ground rod recommended, radial network optional but beneficial for 160m

Band Behavior

160 meters:
The antenna behaves as a top-loaded vertical for 160 m. The vertical section does the majority of the radiation. The result is efficient low-angle DX performance, especially when installed with good soil contact and minimal ground loss.

80 meters:
At 38–41 m, the wire forms a full-wave end-fed on 80 m. This results in a very high-impedance feedpoint, which the 68:1 transformer brings down to match coax. The pattern favors low-angle lobes with moderate directionality, excellent for DX.

Why It Works

  • Long vertical section = strong low-angle DX signal on 160m
  • Full-wave resonance on 80m = efficient pattern with no traps
  • Single feedpoint, simple deployment, only a ground rod required
  • Radials improve 160m further, but are not critical for 80m

80/40m End-Fed Inverted L with 70:1 Transformer

Geometry & Design

  • Wire length: ~38–41 meters
  • Feedpoint height: Minimum 1 m, ideally 2–5 m
  • Vertical section: At least 15 meters, remaining wire horizontal or sloped
  • Matching: 70:1 transformer
  • Grounding: Single ground rod is sufficient

Band Behavior

80 meters:
The wire forms a full-wave end-fed on 80m. This produces low-angle lobes, with high radiation efficiency and mild directionality. The long vertical leg ensures that a significant part of the radiation is vertical, favoring long-distance contacts.

40 meters:
On 40m, the wire becomes 2 wavelengths long. This results in a more complex but multi-lobe low-angle DX pattern, with gain depending on orientation. Despite being non-resonant in a classical sense, the pattern supports excellent long-haul performance.

Why It Works

  • Vertical section contributes to low-angle radiation on both bands
  • Full-wave operation on 80m = no traps, no losses
  • Long-wire behavior on 40m with strong low-angle gain lobes
  • Only a ground rod is required for transformer reference

Transformer Impedance Ratios: Why 68:1 and 70:1?

Both designs present very high feedpoint impedances, often in the 3k–5kΩ range depending on band, height, and surroundings. The transformer ratios are chosen empirically to:

  • Flatten SWR around band centers
  • Keep core losses low
  • Maintain stability without tuning

The difference between 68:1 and 70:1 isn't critical. These values simply work well in practice for these specific wire lengths and bands.

Summary Table

Configuration Wire Length Bands Transformer Vertical Height Grounding Key Advantage
160/80m Inverted L 79–81 m 160 + 80 m 68:1 ≥15 m Ground rod (+ radials optional) True vertical radiation on 160m
80/40m Inverted L 38–41 m 80 + 40 m 70:1 ≥15 m Ground rod only Directional DX pattern on 40m

Conclusion

Both antennas are purpose-built DX solutions for operators who want maximum performance with minimum complexity. Installed properly — with a 15-meter vertical leg and a simple ground rod — they deliver:

  • Excellent low-angle radiation on all bands
  • No traps, no tuning, no moving parts
  • Strong performance over thousands of kilometers

If you only have room for one wire, these end-fed inverted Ls are about as good as it gets.

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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.