VertiCore 5/8th: A Special but More Efficient Antenna for 10-12m Band

A Classic Design, Reimagined

The 5/8 λ vertical has long been a favourite for the 10 and 12 meter bands—especially for those chasing DX. At RF.Guru, we reworked the classic formula into the VertiCore 5/8th 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 and 12 m use pure-length aluminium 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 on 11–12 m), where the antenna briefly passes through a match
  • A second broader and deeper SWR dip on the target band (e.g., 10 m), where the impedance becomes more resistive and usable

This dual-dip behaviour 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 and 12 m, especially when installed with a proper ground plane and without lossy matching elements.

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 optimised 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.

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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.