Tuning Advice for EFLW Antennas
End-Fed Long Wire (EFLW) Antennas: Setup and Optimization Guide
The End-Fed Long Wire (EFLW) antenna is simple to deploy and surprisingly forgiving when it comes to tuning, making it ideal for multiband HF use. Follow these steps to ensure consistent performance and reliable operation across the HF spectrum.
1. Initial Setup
- Mounting Height: Aim for 6–10 meters for general use. Lower heights work fine for NVIS on 80m and 40m.
- Clear Area: Keep the wire away from metal objects, roofs, or dense trees to avoid detuning.
- Feedpoint Position: Ensure the feedpoint is well-supported and has a proper ground reference or counterpoise.
2. Measure and Adjust SWR
- Use an antenna analyzer or SWR meter to check resonance across your target bands.
- Adjust the Wire Length:
- If too long: Resonant frequencies will be below the desired band. Fold back small sections (5–10 cm) and re-measure. Folding Back vs. Cutting Wire Antennas: Essential Tips for Optimal Performance
- If too short: Resonances will appear above your target band — add wire until resonance lowers appropriately.
3. Environmental Adjustments
- Recheck tuning after major weather changes or seasons — moisture and temperature shifts can slightly alter resonance.
- If tuning drifts, inspect for loose connections or corrosion at the feedpoint and transformer.
4. Optional Antenna Tuner
- Most EFLW systems with a 9:1 unun will cover multiple bands, but a tuner improves match on edge frequencies and non-resonant spots.
5. Proven Wire Lengths
The following lengths are tested for use with a 9:1 unun and a suitable tuner. Each avoids strong resonances and provides a stable match across bands:
- 21.64 m — Works best for 40–10 m, usable on 80 m but with reduced efficiency.
- 36.27 m (alt: 35.5 m) — Covers 80–10 m with moderate SWR on 80 m, marginal on 160 m.
- 50.6 m (alt: 49.38 m) — Extends to 160–10 m, though 160 m performance remains a compromise.
Typical SWR Behavior (No Tuner)
(Indicative values — actual readings depend on installation height, counterpoise, and ground conditions.)
| Band | Typical SWR Range | Notes |
|---|---|---|
| 160 m (1.8 MHz) | 5:1 or higher | Shorter wires struggle; tuner strongly recommended. |
| 80 m (3.5–4 MHz) | 2:1–4:1 | 36 m length performs reasonably; tuner improves results. |
| 40 m (7 MHz) | 1.5:1–3:1 | Usually within good matching range for most lengths. |
| 20 m (14 MHz) | 1.5:1–2.5:1 | Highly efficient band for EFLW systems. |
| 15 m (21 MHz) | 1.5:1–3:1 | Depends on length; usually good performance. |
| 10 m (28–29.7 MHz) | 1.5:1–2.5:1 | Most lengths exhibit low SWR here. |
Key Notes
- High Impedance Variations: A 9:1 unun reduces mismatch but cannot provide a perfect match across all HF bands.
- Counterpoise or Ground: A proper counterpoise dramatically improves efficiency and SWR consistency.
With a quality tuner, the EFLW system becomes extremely flexible and capable of covering every HF band effectively.
Conclusion
The End-Fed Long Wire is a reliable and forgiving multiband antenna. With correct length selection, grounding, and minor tuning, it can provide excellent results from 160 m to 10 m for both DX and NVIS use.
Mini-FAQ
- Do I need a counterpoise? — Yes. Even a short counterpoise improves current balance and reduces feedline radiation.
- Is a 9:1 unun the best match? — For general multiband use, yes. However, efficiency on higher bands decreases compared to resonant designs.
- Can I skip the tuner? — Only if SWR is acceptable on your primary bands. A tuner unlocks full multiband coverage.
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