VertiCore 5/8th: A More Efficient Antenna for 4M 6M 10M and 12M Band
Quick Comparison — 5/8 λ vs 1/4 λ
| Aspect | 5/8 λ Vertical (VertiCore 5/8th) | 1/4 λ Vertical (VertiCore 1/4th) |
|---|---|---|
| Best bands | 10 m, 12 m, 6 m, 4 m — practical height, stronger low-angle lobe | 15 m, 17 m, 20 m — practical height with excellent results |
| Typical height | ~0.625 λ (taller; ideal on 10/12/6/4 m) | ~0.25 λ (shorter; ideal on 15–20 m) |
| Elevation pattern | Two lobes; dominant low-angle DX lobe on supported bands | Single lobe; clean low-angle with good radials |
| Bandwidth / SWR | Characteristic dual SWR dips with broad usable region | Stable SWR across the target band |
| Matching | Designed for near 50 Ω with clean geometry; no lossy coils/stubs | Direct 50 Ω with proper radial plane; no coils |
| Practicality by band | Shines on 10/12/6/4 m; above 12 m the size grows with less added benefit | Best pick for 15–20 m; 5/8 becomes unwieldy there |
| Bottom line | Choose 5/8 λ for 10/12/6/4 m to maximize low-angle DX | Choose 1/4 λ for 15–20 m for size, simplicity, and efficiency |
A Classic Design, Reimagined
The 5/8 λ vertical has long been a favorite for the 10 m and 12 m bands—especially for those chasing DX. At RF.Guru, we reworked the classic formula into the VertiCore 5/8th, now also available for 6 m and 4 m, to deliver better performance without the usual compromises.
No Coils, No Stubs, Just Clean RF
Unlike many commercial designs that resort to lossy coils or tuning stubs, the VertiCore 5/8th monoband verticals for 10 m, 12 m, 6 m, and 4 m use pure-length aluminum radiators and 45° angled rigid radials. The result? Minimal loss, improved current taper, and a cleaner impedance profile.
Why the Feedpoint Is Raised
We position the feedpoint 30 cm above the base of the vertical, placing it right at the radial plane. This:
- Improves current distribution on both the radiator and radials
- Enhances low-angle radiation
- Brings the feedpoint closer to X ≈ 0, near 50 Ω purely resistive
- Reduces common-mode current susceptibility on the coax
Understanding the Two SWR Dips
A 5/8 vertical like the VertiCore 5/8th doesn't behave like a 1/4-wave. It’s longer than resonance, and that causes:
- A first shallow SWR dip (often slightly off the amateur allocation), where the antenna briefly passes through a match
- A second broader and deeper SWR dip on the target band (e.g., 10 m or 6 m), where the impedance becomes more resistive and usable
This dual-dip behavior is typical for 5/8 λ designs and is not a flaw—rather, it’s a feature. The second dip is what provides the usable bandwidth and efficient matching across the entire band.
Two Radiation Lobes – But Only One Matters
5/8 λ antennas produce two elevation lobes:
- A higher-angle lobe (not useful for DX)
- A stronger low-angle lobe, close to the horizon—ideal for long-haul contacts
This low-angle radiation is the key reason why the VertiCore 5/8th is preferred for DX on 10 m, 12 m, 6 m, and 4 m, especially when installed with a proper ground plane and without lossy matching elements.
- 5/8 λ (VertiCore 5/8th) — Strong low-angle lobe and excellent DX performance where the physical height is still practical: 10 m, 12 m, 6 m, 4 m.
- 1/4 λ — Above ~12 m (e.g., 15 m, 17 m, 20 m), a 5/8 λ gets very tall and its advantage narrows; a well-implemented 1/4 λ thrives there.
Rigid Radials, Rigid Engineering
Our rigid 45° radials aren’t just aesthetic—they:
- Improve impedance stability
- Create a consistent radial field for repeatable low-angle patterns
- Withstand weather without sagging or detuning
Conclusion
The VertiCore 5/8th is more than just a longer vertical—it’s a precision-built monoband antenna optimized for low-angle gain, broader match bandwidth, and clean, efficient radiation.
Antenna performance isn’t about marketing tricks—it’s about geometry, current, and grounding.
Mini-FAQ
- Which bands are covered? — 10 m, 12 m, 6 m, and 4 m as individual monoband builds.
- Do I need a tuner? — No, each is a monoband antenna designed for direct 50 Ω feed.
- Why no matching coils? — Coils add loss. The VertiCore uses pure-length radiators instead.
- What about DX performance? — Optimized for strong low-angle lobes, ideal for long-haul contacts.
Interested in more technical content? Subscribe to our updates for deep-dive RF articles and lab notes.
Questions or experiences to share? Feel free to contact RF.Guru.