Why the EFOC17 is the Better Choice for 40M to 10M Operation

When choosing an efficient and reliable wire antenna for 40m to 10m operation, two popular options come to mind: the EFOC17 and the EFHW4010. While both antennas cover similar frequency ranges, the EFOC17 offers better efficiency, broader band coverage. Here’s why the EFOC17 is the superior choice.

1. Impedance Matching: A Crucial Difference

  • EFOC17: Uses a 4:1 impedance transformer, meaning it works with a lower impedance compared to a traditional EFHW.
  • EFHW4010: Uses a 49:1 impedance transformer, stepping down the high-impedance feedpoint (2,500Ω to 5,000Ω) to 50Ω.

💡 Why does this matter?

  • The 4:1 transformer in the EFOC17 results in lower losses and improved efficiency.
  • The 49:1 transformer in the EFHW4010 can introduce higher core losses, particularly at high power levels, due to the extreme impedance transformation ratio.

2. Counterpoise and Radiation Efficiency

  • EFOC17: Requires a 3.7m counterpoise (integrated in the coax shield), making it an offset-fed antenna rather than a pure EFHW.
  • EFHW4010: Functions without an explicit counterpoise but can benefit from a ground or radial system.

💡 Why does this matter?

  • The EFOC17’s counterpoise balances the current flow, reducing unwanted feedline radiation.
  • The EFHW4010, relying solely on high-impedance matching, may suffer from higher common-mode currents, leading to potential RFI issues.

3. Band Coverage: EFOC17 Wins

  • EFOC17: Covers 40m, 30m, 20m, 17m, 15m, 12m, and 10m.
  • EFHW4010: Covers only 40m, 20m, 15m, and 10m.

💡 Why does this matter?

  • The EFOC17 provides access to 30m and 17m, two important bands for CW and digital mode operators.
  • The EFHW4010 lacks 30m and 17m, making it less versatile.

4. Power Handling & Efficiency

  • The EFOC17 can handle higher power, which is crucial for high-power stations and contesting.
  • The lower impedance transformation (4:1 vs. 49:1) means the EFOC17 has lower core losses, making it more efficient at high power.

5. Installation and Practicality

  • EFOC17: Needs a coax choke to prevent common-mode currents but is generally more efficient and flexible.
  • EFHW4010: Easier to install as a pure EFHW, but may have higher loss and impedance mismatch issues at certain frequencies.

💡 Why does this matter?

  • If properly installed, the EFOC17 delivers more stable performance across all supported bands.
  • The EFHW4010 may require tuning or adjustments to improve efficiency and manage high SWR on certain bands.

Final Verdict: EFOC17 is the Superior Choice

✅ Better efficiency with a 4:1 transformer (lower loss than 49:1). 
✅ More band coverage (includes 30m & 17m). 
✅ Higher power efficiency.
✅ Lower voltage stress on the transformer = improved durability.
 ✅ Balanced counterpoise design minimizes unwanted RF issues.

While the EFHW4010 is a simple and effective EFHW, the EFOC17 provides a more efficient, broader-band, and higher-efficiency-power alternative. For operators who want better performance across 40m to 10m, the EFOC17 is clearly the better choice.

Article written by Joeri Van Dooren, ON6URE – RF engineer, antenna designer, and founder of RF.Guru. With extensive experience in active and passive antenna systems, high-power RF transformers, and custom RF solutions, Joeri shares insights into cutting-edge radio communication technologies.