End‑Fed Half‑Wave Antennas: Energy Efficiency and DX Capabilities
18 m Spiderbeam pole
-
160 m: Efficiency modest (~56%) from ground/transformer losses.
-
80 m: Higher efficiency (~93–97%) with greater radiation resistance.
Band |
Height Rel. to λ (Vertical) |
Low‑Angle (<15°) |
DX |
NVIS |
160 m |
≈0.093 λ |
Weak |
Poor |
Strong |
80 m |
≈0.187 λ |
Moderate |
Moderate |
Excellent |
26 m Spiderbeam pole
-
160 m: Efficiency improves (~65%).
-
80 m: Very high efficiency (~99%+), low ground loss.
Band |
Height Rel. to λ (Vertical) |
Low‑Angle |
DX |
NVIS |
160 m |
≈0.16 λ |
Moderate |
Moderate |
Good |
80 m |
≈0.33 λ |
Strong |
Good |
Moderate |
18 m Spiderbeam pole
-
80 m: Moderate efficiency (~78%).
-
40 m: Higher efficiency (~88–96%).
Band |
Height Rel. to λ (Vertical) |
Low‑Angle |
DX |
NVIS |
80 m |
≈0.187 λ |
Moderate |
Moderate |
Strong |
40 m |
≈0.375 λ |
Strong |
Good |
Moderate |
26 m Spiderbeam pole
-
80 m: Good (~89%).
-
40 m: Very high (~94%).
Band |
Height Rel. to λ (Vertical) |
Low‑Angle |
DX |
NVIS |
80 m |
≈0.33 λ |
Strong |
Good |
Moderate |
40 m |
≈0.66 λ |
Very Strong |
Excellent |
Weak |
EFHW4020 — Sloper / Flattop
Flattop @ 10 m
-
40 m: ~0.25 λ height — balanced NVIS/DX; low‑angle moderate, NVIS moderate–strong.
-
20 m: ~0.5 λ height — strong low‑angle DX; NVIS weak.
Band |
Height Rel. to λ |
Low‑Angle |
DX |
NVIS |
40 m |
≈0.25 λ |
Moderate |
Good |
Moderate–Strong |
20 m |
≈0.50 λ |
Strong |
Excellent |
Weak |
Sloper @ 10–12 m feedpoint
-
Slope 30–45° toward target area for best DX focus.
- Primary radiation is toward the low end of the slope; steeper slopes add upward energy for regional work on 40 m.
Flattop
- @ 10 m (~0.5 λ): strong low‑angle radiation, excellent DX.
- @ 6–7 m (~0.3–0.35 λ): moderate low‑angle, good DX; some mid‑angle fill for regional QSOs.
Height |
h/λ (20 m) |
Low‑Angle |
DX |
Notes |
≈10 m |
≈0.50 λ |
Strong |
Excellent |
Best for DX |
≈6–7 m |
≈0.30–0.35 λ |
Moderate |
Good |
More mid‑angle energy |
Sloper
-
30–45° slope toward desired DX azimuth; keep feedpoint as high as practical.
- Dominant lobe points toward the lower end of the wire; use to steer coverage.
Mini‑FAQ
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Is the EFHW16080 efficient on 160 m? — Moderately; ground and transformer losses reduce efficiency, but NVIS is strong.
-
Does a taller mast help? — Yes. Raising from 18 m to 26 m improves low‑angle DX on 160/80 m.
-
Is grounding mandatory? — Yes. EFHW Inverted‑L needs a short counterpoise or ground stake (plus a choke).
-
Can EFHW8040 do DX on 40 m? — Absolutely. At ~0.66 λ vertical, low‑angle DX is excellent.
-
Why EFHW4020? — Compact 40/20 m dual‑band; easy sloper/flattop install.
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Is the EFHW20 best for 20 m DX? — Yes. A true half‑wave; mount near 0.5 λ for top DX results.
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