End Fed Off Center Antennas: Mounting advice

When installing a wire antenna, avoid over-tightening the wire. It’s best to leave a slight bend or sag. This prevents excessive tension, protects insulators and support structures, and allows for flexibility during wind or temperature changes. A little slack ensures better longevity and stable performance.

For longer wire antennas, consider using a pulley system with a counterweight. This allows the wire to self-adjust under wind or thermal expansion, maintaining consistent tension without overstressing attachment points. The result is reduced risk of breakage and better long-term stability.

Mounting Advice for EFOC Antennas (EFOC29, EFOC17, EFOC8)

EFOC antennas (End-Fed Off-Center) are near-resonant designs. They generally require lower feedpoint heights than EFHW antennas and can be installed in compact gardens as slopers, inverted-Vs, or inverted-Us. Below are mounting recommendations for:

• EFOC29 (80–10m)
• EFOC17 (40–10m)
• EFOC8 (20–10m)

EFOC29 (80–10m) as a Sloper

• DX (20–10m): Slope 30–45°, feedpoint 7–10m. Low-angle radiation improves DX.
• NVIS (80–40m): Steeper slope 60–75°, feedpoint 3–5m. Enhances high-angle NVIS.
• Multi-band: 45° slope at 5–7m provides balanced performance.

Directivity: Dominant radiation is toward the lower end of the slope. Steeper angles produce more upward NVIS energy.

EFOC17 (40–10m) as a Sloper

• DX (20–10m): Slope 30–45°, feedpoint 7–10m improves DX efficiency.
• NVIS (40m): Slope 60–75°, feedpoint 3–5m enhances high-angle NVIS.
• Multi-band: 45° slope at ~5m balances DX and NVIS.

Directivity: Like the EFOC29, main radiation is toward the slope’s lower end, with NVIS components at steeper slopes.

EFOC8 (20–10m) as a Sloper

• DX (20–10m): Slope 30–45°, feedpoint 3–5m. Shorter length allows compact installs.
• Regional: Slope 45–60°, feedpoint 3–4m directs more energy upward for local coverage.
• Small gardens: Compact size makes it space-friendly while still DX-capable.

Directivity: Sharper directivity toward the lower endpoint due to shorter length. Steeper slope angles add NVIS coverage.

General Alternatives

Inverted V

• Best for: Balanced NVIS and DX, especially with EFOC29 and EFOC17.
• Feedpoint: ≥3m, ideally 5–7m for better performance.
• Pattern: Radiation is strongest broadside to the V plane.

Inverted U

• Best for: Limited spaces and DX on higher bands (EFOC8, EFOC17).
• Feedpoint: 3–5m works well due to near-resonance.
• Pattern: Broadside radiation to the U’s open ends.

Technical Considerations

• Near-resonant design means less dependency on feedpoint height compared to EFHW.
• Tuning may still shift with geometry; minor length trimming or tuner use can help.
• NVIS use: feedpoint heights of 3–5m are adequate on 40m and 80m (EFOC17, EFOC29).

Minimum Ground Clearance

These are minimum recommended clearances. For flat-top use, expect compromised performance. In sloper, V, or U configurations, only the ends may approach these values.

Multiple Antennas on One Mast

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