End Fed Half Wave Antennas: Mounting advice
End‑Fed Half‑Wave Antennas: Mounting Advice
Don’t over‑tension the wire. Leave a small sag to absorb wind/thermal movement. On longer spans, use a pulley + counterweight so the wire self‑adjusts without overstressing insulators, supports, or the transformer hardware. This improves longevity and keeps tuning stable.
EFHW16080 — Inverted‑L
18 m Spiderbeam pole
- Solid on 160 m (adequate) and 80 m (good). Keep the far end as high as possible (≥ 3 m). Feedpoint ≥ 3 m AGL.
- NVIS is strong on both bands at this height.
- Requires a ground stake or ground plane (or short counterpoise + choke) for best performance.
26 m Spiderbeam pole
- Better on 160 m, excellent on 80 m. Far end ≥ 3 m; feedpoint ≥ 3 m AGL.
- 80 m offers NVIS + useful DX at this height.
- Ground stake / ground plane still recommended.
EFHW8040 — Inverted‑L
18 m Spiderbeam pole
- 40 m excellent; 80 m good. Far end ≥ 3 m; feedpoint ≥ 3 m AGL.
- On 80 m: good DX and NVIS; on 40 m: excellent DX, moderate NVIS.
- Ground stake / ground plane recommended.
26 m Spiderbeam pole
- Far end ≥ 3 m; feedpoint ≥ 3 m AGL.
- DX improves on both bands; 80 m still supports NVIS when needed.
- Ground stake / ground plane recommended.
EFHW Antenna — Minimum Ground Clearance
These are minimum clearances for the lowest wire points in L/V/U/Sloper layouts (not for flat‑tops). Keep most of the wire well above these values.
| Band | Freq (MHz) | λ | Effective Ground (~0.10 λ) | Normal Ground (~0.05 λ) |
|---|---|---|---|---|
| 160 m | 1.8 | 166.7 m | 16.7 m | 8.3 m |
| 80 m | 3.5 | 85.7 m | 8.6 m | 4.3 m |
| 60 m | 5.3 | 56.6 m | 5.7 m | 2.8 m |
| 40 m | 7.1 | 42.3 m | 4.2 m | 2.1 m |
| 30 m | 10.1 | 29.7 m | 3.0 m | 1.5 m |
| 20 m | 14.2 | 21.1 m | 2.1 m | 1.1 m |
| 17 m | 18.1 | 16.6 m | 1.7 m | 0.8 m |
| 15 m | 21.2 | 14.2 m | 1.4 m | 0.7 m |
| 12 m | 24.9 | 12.0 m | 1.2 m | 0.6 m |
| 10 m | 28.5 | 10.5 m | 1.1 m | 0.5 m |
Multiple Antennas on the Same Mast
| Condition | Recommended Angle | Reason |
|---|---|---|
| Minimum angle | ≥ 90° | Acceptable isolation for many setups. |
| Optimal isolation | 180° | Maximum isolation, minimal coupling. |
| Multiband system | ≥ 120° | Reduces cross‑band pattern interaction. |
| Compact site | ≈ 45° | Works for some HF/Yagis; coupling increases. |
| Resonant wires (EFHW/EFOC/dipoles) | ≥ 120° | Broad patterns need more spacing. |
| Directional (Yagi, etc.) | ≥ 90° | Narrower lobes tolerate closer spacing. |
| Cross‑polarized | ≤ 90° | Polarization difference reduces coupling. |
Mini‑FAQ
- Grounding required? — For EFHWs, a functional RF return is necessary (ground stake/radials/counterpoise + choke). It also helps with static surges.
- Chokes? — Yes. Place a quality common‑mode choke near the feedpoint and another at shack entry to tame feedline current.
- Is Inverted‑L better than Sloper/Flat‑top? — For 160/80 m, Inverted‑L usually delivers better DX angles at practical heights.
- Sag or tight? — Avoid tight spans. Use sag and counterweights for stability and longer life.
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