Before we meet the antenna family
There is no magical wire that has high gain, needs no tuner, occupies no space, costs nothing, and works every band. If somebody finds one, the Blue Tick will probably be the first to bark about it. The good news is that full-size wire antennas can be wonderfully efficient. The trick is choosing a system whose feed line and matching method suit the job.
Efficiency asks how much transmitter power becomes radiated RF rather than heat. Performance adds a second question: where does that radiation go? Height, wire direction, nearby trees and metal, and the antenna’s electrical length on each band all matter. The antenna’s name is only the beginning of the story.
The plain old dipole
The resonant center-fed half-wave dipole is the benchmark. Two equal wire legs meet at the center, where a 1:1 current choke and 50 ohm coax make a tidy, low-loss system on its intended band. It is simple, repeatable, and just about impossible to improve on for a single band without making the project more complicated.
The doublet
A doublet is the versatile general form of a center-fed two-wire antenna. Instead of demanding that it look like 50 ohms on every band, we feed it with 450 to 600 ohm balanced line and use a balanced tuner. That puts the unavoidable multiband mismatch in a transmission line that handles it with very little loss.
For all-around HF work, this is the system to beat. Pick a wire length that supports the lowest band you care about, get it as high and clear as practical, and give the balanced line a route that stays away from gutters, metal siding, wiring, and other electrically nosy objects.
The ZS6BKW
The ZS6BKW is a carefully optimized member of the doublet family. Its roughly 93 to 94 foot top wire and velocity-factor-corrected balanced-line section are chosen to make 50 ohm coax see a friendlier impedance on 40, 20, 17, 12, and 10 meters. With a tuner, it can also work 80, 30, and 15 meters.
It does not create magical gain. It simply makes the feed system less grumpy on several useful bands. That is still an excellent trick. The exact ladder-line length, its velocity factor, the antenna height, and nearby objects all matter, so “close enough” construction is less close than it sounds.
The G5RV
The classic G5RV is about 102 feet of wire with a balanced-line matching section. It was designed as a tuner-assisted system, originally with open wire and 75 ohm main feeder. It is a useful multiband doublet when operated in that spirit.
The common modern mistake is expecting it to be a tuner-free, 50 ohm, all-band antenna. On many bands the coax can see substantial SWR. High-quality coax helps, but it cannot repeal the laws of mismatch. Keep the coax short when it carries high SWR, use a current choke at the transition, and let a good tuner do its job.
The EFHW
An end-fed half-wave, or EFHW, is a half-wave wire fed at its very-high-impedance end through a typical 49:1 transformer. Its enormous advantage is installation flexibility: it can slope from one high tree, turn into an inverted L, or follow a challenging property line.
The tradeoff is that the transformer, insulation, counterpoise, and common-mode choke need to be treated as part of the antenna—not accessories. A sloppy return path can make the coax shield radiate. That may make contacts, but it also makes RF in the shack and unpredictable patterns more likely.
The End Fed OCF
An End Fed OCF—short for end-fed off-center-fed—is a half-wave-style wire system that keeps the matching box and radio connection at one physical end, while making the electrical feed point deliberately off center. The long wire is one side of the antenna; a selected section of the outside of the coax becomes the short second side. In other words, it gives the installation convenience of an end-fed wire while using the more moderate feed-point behavior of an off-center-fed arrangement.
Its practical benefit is multiband flexibility from a single, convenient feed location. Compared with a true EFHW, the feed point can be easier to match because it is not at the extreme high-impedance end of the half-wave. It can be especially useful for one-tree, fence-line, and portable installations where a traditional center feed is awkward. The tradeoff is that the coax route is an intentional part of the antenna: its length and path affect the pattern and match.
For a beginner-friendly look at this layout, including diagrams and a direct comparison with an EFHW, see the earlier post: End Fed OCF and EFHW for Beginners.
The fan dipole
A fan dipole connects several individual resonant dipoles at one feed point. For example, 20, 15, and 10 meter elements can share a single coax feed. Near each intended band, the resonant element does most of the work, so the system can be low loss and delightfully simple to operate.
The extra wires do talk to each other electrically, a behavior called mutual coupling. Give the elements spacing, use spreaders, and trim them only after the antenna is in its final position. If your favorite bands are known in advance, a fan dipole is one of the cleanest ways to cover them.
The off-center-fed dipole
An off-center-fed dipole, often called an OCF dipole, moves the feed point away from the middle of the wire. That deliberate imbalance can put the feed-point impedance in a more usable range on selected harmonic bands. It is a clever multiband compromise, not a magical “anywhere on the wire” trick.
Many OCF designs use a 4:1 current balun plus a separate effective coax choke. That word current matters. The two antenna legs are unequal at the feed point, so unwanted current on the outside of the coax can be especially tempting. Measure the final antenna at its actual height, check the chosen bands, and treat the choke as part of the system rather than an optional decoration.
Which one belongs in your field?
| Your goal | Best fit |
|---|---|
| Broad HF coverage with the least avoidable loss | Doublet with balanced line and a balanced tuner |
| Many popular bands with less tuning drama | ZS6BKW |
| A few favorite bands and one coax line | Fan dipole |
| One band, maximum simplicity and low loss | Resonant center-fed dipole |
| One high support or an awkward property line | EFHW with a robust transformer, deliberate counterpoise, and choke |
| Multiband flexibility from one convenient feed location | End Fed OCF with a deliberate coax return section and correctly placed choke |
| Selected harmonic bands with a coax-fed multiband compromise | Off-center-fed dipole with a suitable current balun and separate choke |
| An existing G5RV already in the air | Keep it, add an appropriate tuner and current choke, and minimize high-SWR coax |
The final word from the field
If the mission is maximum multiband efficiency, use a ladder-line-fed doublet. If the mission is an easy, dependable single-band antenna, use a dipole. If the mission is “my yard has exactly one heroic tree and a fence that does not cooperate,” an EFHW may be the practical answer—just build the whole system properly.
Whatever wire you choose, put real effort into height, feed-line routing, good chokes, and a sensible matching strategy. Those details matter far more than a clever name. The Blue Tick cannot tune the antenna for you, but apparently it is willing to supervise.
Technical references
American Radio Relay League, The ARRL Antenna Book for Radio Communications, 24th edition, 2019; Ian Poole and Steve Telenius-Lowe, editors, Successful Wire Antennas, Radio Society of Great Britain, 2012; L. B. Cebik, W4RNL, The G5RV Antenna System Re-Visited; Joel Hallas, W1ZR, QST review of an end-fed half-wave system, March 2016; Bob Allison, WB1GCM, QST review of a fan dipole, August 2020; and C. Craeye, International Journal of Antennas and Propagation, 2010, on mutual coupling in wire arrays.