Why Your Windom Antenna is Holding You Back — And What to Use Instead
The Windom vs the Offset-Fed Wire Antenna: A Modern Reassessment
In the world of amateur radio, the Windom antenna has long been a go-to multiband solution. Characterized by an off-center feedpoint and a 4:1 balun to transform its typical 200-ohm feed impedance to 50 ohms, it remains popular—but it may not be the best choice anymore.
A new class of offset-fed antennas using a simple unun and a well-defined counterpoise has begun outperforming the classic Windom in many practical scenarios. This article compares both architectures and explains why one is fundamentally better designed for today’s RF environment.
The Classic Windom: What It Is
A Windom antenna typically consists of a wire divided in a 33%/67% configuration, fed with a 4:1 voltage balun and followed by a 1:1 current choke. It was originally designed to provide a multiband solution with reasonably low SWR on several bands.
The Problems with Windoms Today
- Poor Common-Mode Rejection: Voltage baluns do not enforce current balance. This means the coax shield often becomes part of the radiating system, causing RF in the shack and noise pickup. Even some commercially available feedpoint boxes that include both a voltage balun and unun in one enclosure suffer from this issue. These hybrid arrangements may provide a superficial impedance match but fail to address the underlying current imbalance. The result: dissipation of differential-mode energy as heat inside the core due to eddy currents, reducing overall efficiency and compromising power delivery—especially at higher power levels.
- Mismatch on Non-Harmonically Related Bands: The 200-ohm assumption doesn't hold true on all bands. On many bands, the feedpoint impedance can vary widely, leading to poor matching and balun saturation.
- Counterpoise by Accident: The return current path is undefined. In practice, the coax shield acts as the counterpoise, introducing variability, common-mode currents, and unwanted coupling to nearby conductive objects. This is particularly problematic in systems without hybrid current-mode isolation, where the imbalance is never actively corrected. The result is instability in performance, elevated noise floor, and the risk of RF feedback into shack equipment.
- Band-Specific Performance Variability: The antenna’s radiation pattern and efficiency vary greatly across bands, especially when the balun is under stress.
The Modern Offset-Fed Wire: An Intentional Design
Instead of relying on the coax shield as a counterpoise, modern offset-fed antennas use a short wire on one side as a defined ground reference. These antennas use a 4:1 unun to transform impedance and a well-placed 1:1 choke to keep common-mode currents off the feedline.
In some configurations, the counterpoise can be integrated into the coax shield itself, provided a choke is placed at a calculated distance (typically a quarter wavelength on the lowest band of operation). This creates a virtual counterpoise of controlled length and behavior.
Why It’s Better
- Controlled Return Path: The short wire—or a properly spaced choke on coax—acts as an intentional counterpoise, not a parasitic one. This stabilizes the current flow and reduces unwanted feedline radiation.
- No Need for a Balun: Because the feed is unbalanced by design, a unun is a better match for this system.
- Lower Noise and RFI: With the feedline isolated from the radiating structure, the system picks up less noise and is less likely to cause interference.
- Greater Efficiency: Losses in the unun are typically lower than those in a stressed voltage balun. Combined with proper choke placement, efficiency improves noticeably.
Note: While some designs use a 6:1 unun, we do not offer high-power 6:1 ununs due to core saturation risks at QRO levels. For more on this, see: Why We Don’t Build a 6:1 Unun for High Power Applications
Comparison Table
| Feature | Windom (200-ohm Balun + Choke) | Offset-fed Wire with Unun |
|---|---|---|
| Counterpoise | Coax shield (unintended) | Short wire or coax segment with choke (intentional) |
| Balun Type | 4:1 voltage balun | 4:1 unun |
| CMC Rejection | Poor (non-hybrid), Moderate (hybrid) | Excellent (with choke) |
| RFI/Noise | Often high | Low |
| Feedline Radiation | Likely | Rare |
| Efficiency | Variable | High |
| Pattern Stability | Poor on some bands | Predictable |
Conclusion
The Windom has served generations of hams well, but its reliance on imperfect balancing and undefined current paths makes it a poor match for today’s noisy environments and modern expectations.
The unun-fed offset antenna with an intentional counterpoise—either as a short wire or properly spaced choke on coax—is not just a small improvement. It’s a fundamentally better design. If you're serious about performance, stability, and clean signal handling, it’s time to leave the Windom behind.
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Written by Joeri Van Dooren, ON6URE – RF, electronics and software engineer, complex platform and antenna designer. Founder of RF.Guru. An expert in active and passive antennas, high-power RF transformers, and custom RF solutions, he has also engineered telecom and broadcast hardware, including set-top boxes, transcoders, and E1/T1 switchboards. His expertise spans high-power RF, embedded systems, digital signal processing, and complex software platforms, driving innovation in both amateur and professional communications industries.