MultiBand End-Fed Antennas
We offer three types of multiband end-fed wire antennas: (End-Fed Antennas Explained)
- End-Fed Off-Centre (EFOC)
- End-Fed Half-Wave (EFHW)
- End-Fed Long Wire (EFLW)
Use the sliders below to find out which antenna is best suited to your available space. Span refers to the horizontal space required to install the antenna as a flat-top.
For flat-top and sloper configurations with the feedpoint high, the vertical space should be set to 0. For inverted L and inverted U configurations, adjust the vertical space slider to represent the total vertical space available.
Click on the antenna type to go the specific product page of the antenna !
| Antenna Type | Wire Length | Span | Bands | Optimal Bands |
|---|
Bands not highlighted are between 1:1 and 2.5:1, highlighted in blue require an internal tuner. (SWR less than 3:1) Bands highlighted in red require an external tuner. (SWR higher then 3:1 but lower then 10:1)
The SWR values provided are based on simulations assuming a minimum antenna height of 10 meters above ground in free-space conditions. Actual results may vary significantly depending on the specific installation setup, such as the antenna configuration (e.g., inverted L, sloper), proximity to nearby objects (e.g., buildings, trees, metal structures), type and quality of ground, and other environmental factors. For optimal performance, adjustments to the setup, including antenna orientation, counterpoise length, and matching network, may be required. A tuner may also be necessary for certain bands to achieve the best match.
The Optimal Bands row indicates the frequency bands where the antenna provides the best performance from a radiation perspective. These bands correspond to the antenna being resonant or near-resonant (e.g., a half-wavelength, full wavelength, or low harmonic multiple). On these bands, the radiation pattern is efficient, with low-angle lobes suitable for long-distance DX communications.
For non-optimal bands, the antenna’s length creates multiple high-angle lobes or excessive nulls in the radiation pattern. This reduces the antenna’s ability to efficiently radiate at the desired angles for DX communications. While long-distance contacts are unlikely, these bands may still be usable for local or regional communications, especially if NVIS (Near-Vertical Incidence Skywave) propagation is supported. (160M-30M bands)
| Type | Feedpoint Height | Resonance | DX Radiation Pattern | Bandwidth | Efficiency |
|---|---|---|---|---|---|
| EFOC | 5–10m | Near-Resonant | Practical | Moderate | High |
| EFHW | ≥10m | Resonant | Excellent | Narrow | High |
| EFLW | 2–5m | Non-resonant | Practical | Broad | Good |
| Configuration | EFHW | EFOC | EFLW |
|---|---|---|---|
| Flat-Top | Excellent for DX on resonant bands | Good for multi-band operation | Broad coverage, may need tuning |
| Sloper | Great for DX with high feedpoint | Good for directional DX | Flexible, easy to install |
| Inverted-L | Best for low bands (80m, 160m) | Good for low-band multi-band use | Compact design for low bands |
| Inverted-U | Balanced multi-band performance | Good NVIS and DX balance | Works well for space-constrained setups |
Summary
The End-Fed Off-Center (EFOC) a near-resonant antenna with a 4:1 UNUN is ideal for compact, multi-band setups where practical DX capability is needed across multiple bands. It may require a tuner for less optimal bands.
The End-Fed Half-Wave (EFHW) a resonant antenna (on it's even and odd harmonics) with a 56:1 (or even higher ratio) transformer excels at DX on resonant bands with very high efficiency. It is best for operators focusing on specific bands that fall in the even or odd harmonics.
The End-Fed Long Wire (EFLW) a non resonant antenna with a 9:1 UNUN offers broad HF coverage for casual operation or monitoring. It works well across all bands with a tuner but may develop inefficient patterns at higher harmonics.
End-Fed Antennas Explained
End-fed antennas are fed at one end, unlike center-fed antennas, which are fed at their physical and electrical center. This “unbalanced” feed configuration inherently places the feedpoint off-center. To complete the RF current circuit, the shield of the coaxial cable often acts as the “coaxial counterpoise,” providing the necessary return path for the alternating currents. Below is an explanation of three types of end-fed antennas:
1. End-Fed Off-Center (EFOC)
- Description: An end-fed variant fed slightly away from the very end (off-center).
- Reason for Off-Center Feeding: Moving the feed point slightly away from the high-impedance tip reduces extreme impedance mismatch, making matching easier.
2. End-Fed Half-Wave (EFHW)
- Description: A half-wavelength long antenna fed at one end. The current peaks at the center, and voltage peaks at the ends.
- Reason for Off-Center Feeding: An EFHW is fed at the end primarily because of its electrical characteristics as a half-wavelength antenna (being resonant at the odd and even harmonics), feeding at the end means dealing with a very high impedance (2,000–5,000 ohms), typically handled by a matching transformer (49:1, 56:1, 64:1, 68:1, 70:1 and 75:1).
3. End-Fed Long Wire (EFLW)
- Description: A non-resonant antenna, usually longer than a half-wavelength, operating over multiple frequencies.
- Reason for Off-Center Feeding: Feeding at one end makes it convenient to deploy, but it lacks natural current balance, requiring a ground or coaxial counterpoise for the rf current.
Summary
All end-fed antennas are "off-center" because of their asymmetry. The counterpoise design depends on the type:
- EFOC: Short coaxial counterpoise.
- EFHW: Very short depending on design and choking capabilities of the transformer.
- EFLW: Longer coaxial counterpoise due to its non-resonant behavior.
In our End-Fed antennas, part of the feedline functions as the counterpoise, and, if necessary, can be isolated using a 1:1 current balun or choke or ground connection.
This approach provides a more practical and streamlined solution compared to deploying and managing a separate counterpoise wire.
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.