VertiCore Monoband Series: 1/4 λ and 5/8 λ — Technical Overview
Updated: 2025-08-19 — Technical overview validated against VertiCore (1/4 λ & 5/8 λ) with elevated 45° feedpoint radials (¼ λ each).
VertiCore 1/4th and VertiCore 5/8th are purpose-built monoband verticals that refine the classics for modern stations. Both use marine-grade materials, integrated elevated 45° radials (¼ λ) at the feedpoint, and clean 50 Ω implementations—no lossy traps, stubs, or “tricks.” Choose the geometry that fits your band and height constraints to unlock reliable, low-angle performance.
Heavy-duty aluminum radiators, elevated 45° ¼ λ radials, and stainless fittings. Feedpoint aligned with the radial plane for stability. No coils, no stubs—just efficient current distribution.
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 | Taller radiator; ¼ λ elevated radials at 45° | Shorter radiator; ¼ λ elevated radials at 45° |
| Elevation pattern | Two lobes; dominant low-angle DX lobe on supported bands | Single lobe; clean low-angle with elevated radials |
| Matching | Near 50 Ω with clean geometry | Direct 50 Ω with elevated radial plane |
VertiCore 5/8th — Why It Excels on 10/12/6/4 m
On higher bands, a 5/8 λ radiator plus elevated ¼ λ radials yields a strong low-angle lobe without resorting to lossy loading. VertiCore 5/8th uses a pure-length aluminum radiator and rigid 45° ¼ λ radials for minimal loss, good current taper, and a clean impedance profile.
VertiCore 1/4th — The Reliable Workhorse for 15/17/20 m
The quarter-wave gets the fundamentals right: robust efficiency, forgiving matching, stable patterns. VertiCore 1/4th uses a 35 mm, 2 mm-wall aluminum radiator with elevated 45° ¼ λ radials for a compact but uncompromised monoband on 15/17/20 m.
Specs at a Glance
| Model | Bands | Radiator | Radials | Feedpoint |
|---|---|---|---|---|
| VertiCore 1/4th | 15 m, 17 m, 20 m | One-piece marine-grade aluminum, Ø35 mm, 2 mm wall | Elevated 45° radials — exact ¼ λ | Aligned with radial plane |
| VertiCore 5/8th | 10 m, 12 m, 6 m, 4 m | Aluminum, sized for 5/8 λ (no loading coils) | Elevated 45° radials — exact ¼ λ | Aligned with radial plane |
Operating Bands & Angles
- 1/4 λ: Broad resonance, forgiving SWR, efficient on 15–20 m with ~18–24° takeoff angles.
- 5/8 λ: Narrower tuning but higher efficiency; ~10–16° takeoff angles ideal for DX on 10/12 m and sporadic-E on 6/4 m.
Per-Band Heights Guide
Assumes elevated 45° radials with exact ¼ λ length per band and ≥ 0.5 m tip clearance. Heights refer to the bottom/feedpoint above local ground (AGL).
| Band | Geometry | Recommended Bottom / Feedpoint Height (AGL) | Typical Takeoff Angle* |
|---|---|---|---|
| 20 m | 1/4 λ (VertiCore 1/4th) | 4.1–4.5 m | ~22–24° |
| 17 m | 1/4 λ (VertiCore 1/4th) | 3.3–3.6 m | ~20–22° |
| 15 m | 1/4 λ (VertiCore 1/4th) | 2.8–3.2 m | ~18–20° |
| 12 m | 5/8 λ (VertiCore 5/8th) | 2.5–2.8 m | ~14–16° |
| 10 m | 5/8 λ (VertiCore 5/8th) | 2.2–2.5 m | ~12–14° |
| 6 m | 5/8 λ (VertiCore 5/8th) | 1.4–1.7 m | ~10–12° |
| 4 m | 5/8 λ (VertiCore 5/8th) | 1.1–1.4 m | ~8–10° |
*Angles are indicative for the VertiCore with integrated elevated 45% ¼ λ radials; surroundings and soil will shift them slightly.
- Vertical drop per radial at 45° is
0.707 · (¼ λ). With a clearance target C ≈ 0.5 m, the minimum feedpoint height isH_min ≈ 0.707·(¼ λ) + 0.5. - Examples (mid-band λ): 20 m → ¼ λ≈5.3 m → Hmin≈3.75+0.5≈4.25 m; 10 m → ¼ λ≈2.63 m → Hmin≈1.86+0.5≈2.36 m.
- If you must run lower heights, shorten the radials accordingly: for fixed H and clearance C, the longest allowable radial is
L_r ≤ (H − C)/0.707. - Coax: depart at right angles to the radial fan for the first meters to reduce common-mode pickup.
Radial Strategy
- Integrated elevated system: Four 45° radials at the feedpoint (each ¼ λ). Keep symmetry for repeatable impedance and clean patterns.
- Clearance: Aim for ≥ 0.5 m tip clearance to surface/roof; raise the feedpoint or shorten radials if needed.
Maintenance
For all aluminum-to-aluminum interfaces, apply AL-1100 aluminum paste during assembly to prevent corrosion and keep contact resistance low. In coastal/polluted environments, re-apply every 2–3 years during inspection.
Apply AL‑1100 aluminum paste on all aluminum joints during assembly to prevent galvanic corrosion and keep contact resistance low.
How often? One thorough application at install is typically sufficient. In coastal/polluted environments, reapply every 2–3 years during inspection.
VSWR Sweep
(Indicative) — measured at the feedpoint with the integrated choke (if used) and the integrated elevated 45° ¼ λ radials. Expect small shifts with surroundings.
VertiCore 1/4th
VertiCore 5/8th
Radiation Patterns
Patterns shown are simplified models for clarity — see why we use simplified models and not NEC. Real-world results vary with soil, height, and surroundings.
VertiCore 1/4th
-
20 m
-
17 m
-
15 m
VertiCore 5/8th
-
12 m
-
10 m
-
6 m
-
4 m
Set the feedpoint so ¼ λ elevated radials clear the surface by ≥ 0.5 m. Keep symmetry, route coax at right angles initially, and re-torque hardware after storms.
Mini-FAQ
- Which model is better for DX? — 5/8 λ on 10/12/6/4 m (lower takeoff); 1/4 λ is excellent on 15/17/20 m.
- Do I need a tuner? — No. Both are monoband, designed for 50 Ω feed when properly installed.
- Why no loading coils? — Coils/stubs add loss. VertiCore uses pure-length radiators with elevated ¼ λ radials.
- Maintenance? — Apply AL-1100 on joints; re-check seasonally.
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