Classic Windom Antenna
The Windom is commonly credited to Loren Windom, W8GZ, who published the design in the late 1920s: an off-center-fed half-wave wire matched at a point roughly a third of the way along its length, using a single wire as the feeder — no second conductor, no balun, nothing balanced about it at all. That single-wire feed is the historically accurate, distinguishing feature of the original design, and it's genuinely different hardware from the coax-and-4:1-balun antennas that carry the Windom name today. This guide builds the authentic single-wire-fed version and is upfront about why nearly everyone moved on from it.
What made the original design work
An off-center feedpoint on a half-wave wire naturally lands somewhere between the very low impedance at the center and the very high impedance at the ends. Windom found empirically that tapping in around a third of the way from one end gave an impedance in the few-hundred-ohm range — high, but low enough that a single wire run to the station (rather than a matched two-wire line) could be coupled into a period-correct link-coupled transmitter tank circuit reasonably well.
Single wire feeder -> couples into a link-coupled/unbalanced tuner, no balun used
Why this isn't what's usually built as a "Windom" today
The antennas most hams now call a Windom — including the OCFD and Carolina Windom designs already on this site — keep the same off-center feedpoint idea but feed it with coax through a 4:1 current balun instead of a bare single wire. That's a real, practical improvement, and it's why those pages exist separately: they are the modern evolution of this idea, not the same hardware.
- OCFD (already on this site): off-center feed, coax + 4:1 balun, no single-wire feeder.
- Carolina Windom (already on this site): OCFD plus an added decoupling stub/vertical radiating section.
- Classic Windom (this guide): the original single-wire-feeder hardware, historically accurate.
The real downsides of a single-wire feed
A single wire with no return conductor is inherently unbalanced and radiates along its entire run to the station — which means the feeder itself becomes part of the antenna system in an uncontrolled way. In practice that means RF can show up in the shack, the feeder's exact length and routing affect tuning, and nearby metal or the operator's own body can shift the match. None of this is a myth or an exaggeration — it's the documented reason the balun-fed OCFD/Carolina Windom designs largely replaced this approach.
Why build it anyway
Some builders want the historically accurate experience, or are experimenting with period-correct link-coupled matching. If that's the goal, this guide gets you there faithfully. If the goal is simply "a Windom-style multiband wire that works well with a modern rig," the OCFD or Carolina Windom pages are the better starting point.
Installation options
All three approaches keep the same off-center-fed wire and single-wire feeder — the difference is how the wire itself is supported.
- Flat-top between two supports: the standard historical install, keeping the wire level and the feedpoint at a consistent height.
- Inverted-V from a single mast: workable with one high support, though asymmetric leg lengths make the pattern somewhat less predictable than a level flat-top.
- Experimental/period-correct station setup: many builders pair this design with a link-coupled tuner and tube-type final for an authentic period build, rather than a modern solid-state rig.
| Parameter | 80m example | 40m example | Notes |
|---|---|---|---|
| Total wire length | ~124.8 ft | ~62.4 ft | Standard half-wave dipole length for the design band |
| Short leg (feed side) | ~44.9 ft | ~22.5 ft | ~36% from one end — matches the empirically-found low-hundreds-of-ohms tap point |
| Long leg | ~79.9 ft | ~39.9 ft | Remainder of the wire |
| Single-wire feeder | Non-resonant length | Non-resonant length | Avoid half-wave multiples of the feeder itself — same principle as tuning a random-wire feed |
Classic Windom Dimension Calculator
Materials for Classic Windom
Building the Classic Windom
The wire and supports are simple; the single-wire feeder is where this build actually differs from a modern OCFD, and where the most care is needed.
Choose your design frequency and cut the wire
Use the calculator above to get the total length and the short/long leg split, and cut one continuous wire to that total length.
Install the offset feedpoint
Mark the wire at the short-leg distance from one end and install a feedpoint insulator/bracket there — this is the tap point, not the center.
Attach end insulators
Tie off both ends of the wire to egg insulators, ready for support rope.
Raise the antenna
Hoist the wire between two supports, flat-top if possible, keeping the offset feedpoint at whatever height your site allows.
Run the single-wire feeder to the station
Connect a single feeder wire to the feedpoint bracket and route it to your station entry point, choosing a length that avoids half-wave multiples on your working frequency.
Bring the feeder through a dedicated entry point
Use a feed-through entry insulator rather than routing the bare wire through a window or door frame.
Connect to a link-coupled or unbalanced tuner
Connect the feeder to a tuner designed for unbalanced, single-wire-style feeds, along with a solid station ground for the return path.
Tune and check for RF-in-the-shack symptoms
Tune for an acceptable match, then check for RF feedback symptoms (rig lockups, TVI, "hot" microphone or chassis) that are common with single-wire feeds and address them with better grounding or feeder routing.
| Symptom | Most likely cause | Diagnosis | Fix |
|---|---|---|---|
| RF present in the shack | Single-wire feeder radiating along its run, aggravated by weak station grounding | Check for a "hot" mic/chassis or TVI symptoms during transmit | Improve station grounding, reroute the feeder away from other cables, and add a common-mode choke at the entry point — or move to a balun-fed OCFD if it persists |
| Tuning shifts when you touch the tuner or move nearby | Unbalanced single-wire feed is sensitive to nearby objects and body capacitance | Compare the match with hands/body near vs. clear of the tuner and feeder | Expected behavior for this design; for a stable match, switch to a balanced or coax-fed alternative like the OCFD |
| Can't find a good match at all | Feeder length lands on or near a half-wave resonant multiple | Check the feeder length against half-wave multiples of your operating frequency | Change the feeder to a non-resonant length and re-tune |
| Match is workable on the design band but erratic on harmonics | Single-wire feed coupling behaves differently across bands | Sweep SWR across the design band and its harmonics | Treat the design band as primary; less predictable harmonic performance is normal, not a fault |
| High SWR at the design frequency right after building | Leg lengths cut incorrectly, or feedpoint tap installed at the wrong distance | Re-measure the short and long legs against the dimensions table | Re-cut or re-tap the wire to the calculated lengths and re-sweep |
Is this the same as the OCFD already on this site?
No — the OCFD guide covers the modern coax-and-4:1-balun version. This guide builds the original single-wire-feeder hardware Loren Windom actually used.
Is this the same as the Carolina Windom?
No — the Carolina Windom is a coax-fed OCFD with an added decoupling stub/vertical radiating section. Neither of those pieces is part of this original design.
Should I build this one or the OCFD?
Build this one for historical accuracy or period-correct experimentation. Build the OCFD if you just want a practical multiband wire antenna that plays well with a modern rig and doesn't fight RF-in-the-shack problems.
Why no balun on this design?
Because there's nothing to balance — a single-wire feeder is inherently unbalanced by design, which is exactly the historical detail that later balun-fed variants were built to fix.
Can I add a balun to this design to clean it up?
At that point you've effectively built an OCFD — which is a legitimate outcome, but it's a different antenna from the one this guide sets out to build.
Is RF-in-the-shack guaranteed with this design?
Not guaranteed, but common enough that it's worth expecting and planning for with good grounding and careful feeder routing from the start.