End Fed Long Wire Antennas
End-Fed Long Wire (EFLW) Antennas
Non-resonant, end-fed off-center operation with a 9:1 unun and a coax-braid counterpoise. Place the feed-line choke at the specified distance to “tap” ~400–500 Ω so your tuner only does light touch-up.
An EFLW behaves like an end-fed OCF dipole where the coax braid acts as the other leg. The wire is deliberately non-resonant. The 9:1 unun brings the impedance closer to tuner-friendly range, and the choke position (measured from the unun) sets the effective OCF tap near 400–500 Ω. Do not ground the side stud or the coax braid. Vertical or horizontal bends are fine—tree-to-tree, around corners, or as an inverted-L.
EFLW – Compact (41 ft, 71 ft)
Small-lot & portable. Start with 16 ft (41 ft wire) or ~42–50 ft (71 ft wire) choke distance; slide slightly to trim SWR. Bends okay.
EFLW – General Purpose (111 ft, 155 ft)
111 ft → choke ~37 ft. 155 ft → choke ~95 ft (70–95 workable). Use 100 ft coax when targeting 160 m.
EFLW – Extended (173 ft)
Large lots/acreage. Start choke at ~80 ft; adjust for lowest SWR on low bands. Bends & tree-to-tree runs work great.
Wire Lengths, Choke Placements & Minimum Coax
| Wire Length | Start Choke Distance (from 9:1) | Minimum Coax | Typical Bands (light ATU) | Notes |
|---|---|---|---|---|
| 41 ft | ~16 ft | 25 ft+ | 40–6 m | Slide choke ±2–4 ft to trim SWR |
| 71 ft | ~42–50 ft | 50 ft+ | 80–6 m | 42 ft often helps 80 m |
| 111 ft | ~37 ft | 50 ft+ | 80–6 m | Great all-rounder |
| 155 ft | ~95 ft (70–95 workable) | 100 ft (160 m) | 160–6 m | Consider 2× SOFLC for 80/160 m |
| 173 ft | ~80 ft | 100 ft (160 m) | 160–6 m | Strong low-band reach |
Which length should I choose?
Pick your yard size and start with the suggested wire + choke distance. You can bend the wire vertically or horizontally to fit trees and structures. Click on size arrow to see options.
Small Yard / Portable / HOA
- 41 ft → choke ~16 ft → 40–6 m focus.
- 71 ft → choke ~42–50 ft → adds workable 80 m.
- Use 25–50 ft coax. Inverted-L or sloper. Bends are OK (tree-to-tree, corners).
Medium Yard / General Purpose
- 111 ft → choke ~37 ft → solid 80–6 m with light ATU.
- 155 ft → choke ~95 ft → 160–6 m capability (100 ft coax).
- Try an inverted-L; a short horizontal top section often helps tuning.
Large Lot / Acreage
- 173 ft → choke ~80 ft → 160–6 m with better low-band depth.
- Use ~100 ft coax for 160 m; consider 2× SOFLC for stronger CMC isolation.
- Route around trees as needed—vertical and horizontal bends are expected.
Quick-Setup: EFLW Minimal-Tuner Method (open → Print to PDF)
What the choke does
It stops RF on the outer braid at a measured distance to create the effective OCF tap (~400–500 Ω). That’s what minimizes tuner use.
Popular lengths & starting choke distances
- 41 ft → ~16 ft | 71 ft → ~42–50 ft
- 111 ft → ~37 ft | 155 ft → ~95 ft (70–95 workable)
- 173 ft → ~80 ft
5 steps
- Mount the 9:1 unun clear of metal/wet foliage.
- Run wire as sloper, inverted-L, or horizontal—bends are fine.
- Measure from the unun and install the SOFLC choke at the distance above.
- Run coax to the shack (see minimums in the table; use ~100 ft for 160 m).
- Check SWR; slide the choke ±1–5 ft to land the lowest SWR; touch up with ATU.
Tips
- Large-OD coax needs fewer turns; for 80/160 m, a second SOFLC often helps.
- If the unun/choke warms on long TX, reduce power or duty cycle (digital modes).
- Do not ground the side stud or the coax braid—the braid is the counterpoise.
Shopping resonant end-fed OCFs? See our End-Fed OCF (BULLET Series). Explore OCF Antennas and Loop Antennas. Need deeper dives? Visit our Helpful Technical Guides.
