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 highlighted in blue require an internal tuner. (SWR less then 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 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 driven at one end, unlike center-fed antennas, which are fed at their physical and electrical center. This "unbalanced" feed arrangement makes them inherently off-center and necessitates the use of a counterpoise. 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.
- Counterpoise: Typically, a small counterpoise or ground connection is sufficient since the feed point is closer to a lower impedance point than a pure end-fed design.
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 (beeing 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).
- Counterpoise: A short counterpoise or ground connection (depending on feedpoint height versus wavelength) is usually needed to balance the return current.
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 counterpoise for the return path.
- Counterpoise: A longer counterpoise or effective ground system is generally required because the antenna is non-resonant.
Why a Counterpoise is Always Needed
In any end-fed antenna:
- Completing the Circuit: RF energy needs a return path. Without a counterpoise, the feedline or equipment might act as part of the antenna, causing inefficiency and RFI.
- Balancing Current: End-fed antennas lack symmetry. A counterpoise prevents undesired current flow on the coaxial shield, ensuring efficiency and a proper radiation pattern.
Summary
All end-fed antennas are "off-center" because of their asymmetry. The counterpoise design depends on the type:
- EFOC: Small counterpoise.
- EFHW: Very Small counterpoise.
- EFLW: Larger counterpoise due to its non-resonant behavior.
In our End-Fed antennas, the feedline serves as the counterpoise and is isolated using an appropriate 1:1 current balun or choke, offering a more practical solution than managing a separate counterpoise wire.