VertiCore Monoband Series: 1/4λ and 5/8λ — Technical Overview
VertiCore Monoband Series: 1/4λ and 5/8λ — Technical Overview
One band per antenna, a defined radiator and elevated-radial geometry, and a measured feed assembly designed for repeatable RX/TX service without loading coils or traps.
VertiCore is a family of rigid, band-specific passive verticals. The 15, 17 and 20 m versions use 1/4λ radiators; the 4, 6, 10 and 12 m versions use 5/8λ radiators. Both families use four elevated 45° quarter-wave radials and a measured 1:1 balun/feed assembly, but the way each geometry approaches 50 Ω is not identical.
Two Geometries, One System Discipline
| Feature | VertiCore 1/4λ | VertiCore 5/8λ |
|---|---|---|
| Bands | 15 m, 17 m, 20 m | 4 m, 6 m, 10 m, 12 m |
| Radiator | Band-specific 1/4λ aluminium element | Band-specific 5/8λ aluminium element |
| Return system | Four elevated 45° 1/4λ radials | Four elevated 45° 1/4λ radials |
| Feed geometry | Radiator and sloping-radial driving point established as one assembly | Radiator connection and radial plane deliberately shifted upward together |
| Common-mode control | Measured 1:1 balun option at the feed assembly | Measured 1:1 balun option at the feed assembly |
| Pattern intent | Simple monoband vertical response with a controlled return path | Strong low-elevation component in the intended installation |
Neither design uses a loading coil or trap. That does not mean “no matching structure.” The radiator, driving point, radial plane, mast boundary, 1:1 balun and initial coax route together determine the measured input and installed current distribution.
How the Feed Approaches 50 Ω
VertiCore 1/4λ
A straight quarter-wave monopole over an ideal infinite plane is not automatically a 50 Ω antenna. VertiCore uses four elevated radials inclined at approximately 45°. Their geometry changes the return current and driving-point impedance while providing a physically defined counterpoise. The production radiator and radial lengths are band-specific and are measured as a complete assembly.
VertiCore 5/8λ
The 5/8λ version uses an offset driving point. The coax-side connection is moved a short distance upward on the radiating tube, and the radial plane moves upward with it. This samples a different local voltage-to-current ratio and changes the coupling between upper radiator, lower radiator segment and radials. RF.Guru establishes the production position by measurement; it is not a universal offset that can be transferred to a different tube and radial geometry.
The 1:1 balun is not the 50 Ω transformer. The antenna geometry establishes the nominal input impedance. The balun controls unwanted common-mode current on the coax exterior so the feedline does not become an accidental fifth radial or radiator.
Materials and Mechanical Boundary
- Radiators: band-specific marine-grade aluminium tubing without loading coils or traps.
- Radials: four rigid, elevated quarter-wave aluminium conductors arranged symmetrically at approximately 45°.
- Hardware: RVS/INOX 316 stainless fasteners and fittings.
- Feed assembly: product geometry and selected 6 kW or 9 kW 1:1 balun measured as a finished system.
- Maintenance: clean and protect aluminium-to-aluminium joints with AL-1100 aluminium paste; inspect more often in coastal or polluted environments.
Installation Height Is Set by Clearance and RF Behaviour
For a quarter-wave radial of length Lr inclined downward at 45°, its vertical drop is approximately
drop ≈ Lr × sin(45°) ≈ 0.707 Lr
Hfeed ≥ 0.707 Lr + C
C is the required radial-tip clearance above the local surface or accessible area. This is a mechanical clearance calculation, not a universal RF optimum. Ground, roofs, nearby conductors, mast coupling and feedline routing still affect the match and pattern.
- Install all four radials before tuning.
- Keep radial angles and surrounding clearances as symmetrical as practical.
- Route the coax away from the radial plane at right angles initially.
- Measure at the feedpoint or de-embed the feedline.
- Record complex impedance across the intended band, not only the minimum SWR.
- Measure outside-of-coax current after the mast, bonding and final cable routes are present.
Product Verification Sweeps
The following retained plots document RF.Guru product verification configurations. They are evidence for the measured assemblies shown, not a promise that every roof, mast, soil, feedline or nearby conductor will reproduce the trace without adjustment.
VertiCore 1/4λ
VertiCore 5/8λ
Radiation-Pattern Context
The retained diagrams are simplified engineering models intended to show the main pattern trend. They are not calibrated site measurements. Installed elevation angle and realised gain depend on height, ground, radial currents, mast, feedline, nearby structures and loss. See why RF.Guru uses simplified radiation models for the purpose and limits of these diagrams.
VertiCore 1/4λ model set
VertiCore 5/8λ model set
Power Options and Station Boundary
The current VertiCore product page offers 6 kW and 9 kW 1:1 balun service options. RF.Guru measures and tests those assemblies, but the usable station limit remains conditional on frequency, waveform, PEP and average power, duty cycle, tune time, mismatch magnitude and phase, connector/feedline rating, ambient temperature, sun, ventilation and installation. A component rating never overrides station licensing or RF-exposure requirements.
Mini-FAQ
- Which VertiCore bands use 1/4λ radiators? The 15 m, 17 m and 20 m versions use band-specific 1/4λ radiators with four elevated 45° quarter-wave radials.
- Which VertiCore bands use 5/8λ radiators? The 4 m, 6 m, 10 m and 12 m versions use band-specific 5/8λ radiators with four elevated 45° quarter-wave radials.
- How does the 5/8λ version reach approximately 50 Ω? Its radiator connection and radial plane are shifted upward together to create a measured band-specific driving point.
- Does the 1:1 balun create the 50 Ω match? No. The radiator and radial geometry establish the nominal input. The balun controls common-mode current on the coax exterior.
- Are the displayed pattern angles guaranteed at my site? No. The diagrams show simplified trends. Installed height, ground, mast, feedline, radials, surroundings and loss determine the realised result.