The FullHalfWave Series (EF FHW): Dual Half-Wave EFHWs Reimagined for Real-World DX
What if we told you that you could get two half-wave resonant bands — like 80m & 40m or 40m & 20m — from a single end-fed wire, with no lossy resonant traps, no weird current nulls, and no “multi-band magic”? Meet the FullHalfWave series (EF FHW): a next-gen end-fed concept aimed at DX-first performance in practical inverted-L installations.
What Makes It Special
The FullHalfWave antennas are dual half-wave (EF FHW) designs that use a non-resonant trap (current-shaping element) to preserve continuous current flow while subtly shifting the current distribution. This is not a “multi-band compromise” — it is a deliberate build that treats both bands as first-class citizens, even in real-world inverted-L layouts.
Available Variants (Inverted-L)
- FullHalfWave 8040 → ~61.0 m of wire (80m + 40m half-wave)
- FullHalfWave 4020 → ~31.4 m of wire (40m + 20m half-wave)
⚠️ Due to physical length and the way current is shaped, this technique is best suited for these two band combinations. Both deliver excellent results when deployed with enough vertical rise and a clean top run.
Radiation Pattern Comparison (Inverted-L)
FullHalfWave 8040 (80m + 40m)
| Band | Active Wire Section | Layout | Typical Vertical Rise | Indicative Takeoff | DX Rating |
|---|---|---|---|---|---|
| 40m | First ~20.5 m | Inverted-L (vertical + top) | ~10–14 m (if possible) | 15°–25° | ⭐⭐⭐⭐⭐ |
| 80m | Full ~61.0 m | Inverted-L (vertical + long top) | ~10–14 m (more is better) | 25°–40° | ⭐⭐⭐⭐⭐ |
Tip: on 80m, vertical height is king. If you can push the vertical section higher, the low-angle component improves noticeably.
FullHalfWave 4020 (40m + 20m)
| Band | Active Wire Section | Layout | Typical Vertical Rise | Indicative Takeoff | DX Rating |
|---|---|---|---|---|---|
| 20m | First ~10.7 m | Inverted-L (vertical-dominant section) | ~8–12 m | 12°–20° | ⭐⭐⭐⭐⭐ |
| 40m | Full ~31.4 m | Inverted-L (vertical + top) | ~8–12 m | 20°–30° | ⭐⭐⭐⭐⭐ |
Why These Dual EF FHWs Are DX Beasts
- Both bands are engineered to hit half-wave resonance → strong current peaks → high effective radiated power.
- No resonant traps → no narrowband “trap loss” behavior; the element is used for current shaping, not resonance.
- In inverted-L form, you get a practical mix of vertical polarization (for lower angles) and a top section that helps control the current distribution.
- These are not “it tunes somehow” antennas — they are two-band designs with intentional geometry and current control.
Transformer Matching & Feedpoint Behavior
| Variant | Primary Band | Typical Install | Feed Z (Typical Range) | Recommended Transformer |
|---|---|---|---|---|
| FullHalfWave 8040 | 80m | Inverted-L with long top section | ~3.5–4.5 kΩ | 70:1 ✅ |
| FullHalfWave 4020 | 40m | Inverted-L (DX-oriented height) | ~1.8–2.5 kΩ | 49:1 ✅ |
On each design, the non-resonant trap shapes current on the higher band, while staying electrically “quiet” on the lower band — so the full wire still behaves as a clean end-fed half-wave on the low band. In inverted-L deployments, this helps keep both bands efficient without relying on lossy, high-Q resonant trap behavior.
Theory Meets Reality
⚠️ This is currently a theoretical model. Final matching, bandwidth, and real-world noise/common-mode behavior still need field testing. We will update this article with deployment results once test installations are complete.
The FullHalfWave EF FHW Series: 2 bands. Full half-wave resonance. Zero compromise.
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