“Mythbusting the Mythbusters”: 1/4 & 5/8 Verticals Don’t Work the Same
Many hams have heard the claim:
“If it’s mounted near ground with radials, a 1/4-wave vertical and a 5/8-wave vertical perform the same.”
This line, often repeated on blogs like practicalantennas.com, may sound plausible — but it’s wrong. Antenna length, current distribution, and radiation angle absolutely matter.
Why the Claim Is Wrong
The misconception rests on three flawed assumptions:
- That all ground-mounted verticals radiate alike, regardless of length
- That ground loss dominates so much that element length doesn’t matter
- That matching/SWR curves are more important than far-field radiation
In reality, current distribution and radiation angle — both length-dependent — control how your vertical actually performs.
Why Length Matters
1. Current Distribution
- 1/4-wave: Current peaks at the base, tapering quickly to zero at the tip.
- 5/8-wave: Current stays strong higher up the radiator, producing more effective radiation above ground.
This extended taper compresses the radiation pattern downward, producing a lower takeoff angle.
2. Radiation Angle
- 1/4-wave: Main lobe ~25–30° — better for regional/NVIS on lower HF.
- 5/8-wave: Main lobe ~16–18° — excellent for DX at longer distances.
Ground mounting does not erase this difference. Electrical length still governs lobe formation.
3. Impedance Behavior
- 1/4-wave: Naturally ~35–50 Ω. Often matches without added components.
- 5/8-wave: Typically ~20–25 Ω, requiring a stub, coil, or transformer. That’s not a flaw — it’s how you unlock its DX advantage.
Where 5/8-Waves Shine
5/8-wave verticals are especially effective where the radiator remains manageable in physical size:
- 6 m (50 MHz)
- 10 m (28 MHz)
- 12 m (24 MHz)
- 4 m (70 MHz)
On these bands, they provide flatter lobes, extra gain at low elevation, and a real DX advantage over 1/4-wave designs.
Where They Don’t
On bands like 15 m and below, a 5/8-wave becomes too tall (13 m+ on 20 m) and the advantage diminishes. At those lengths, soil loss and installation limits outweigh the DX benefit. A well-matched 1/4-wave is usually the smarter choice.
| Parameter | 1/4-Wave | 5/8-Wave |
|---|---|---|
| Electrical length | 2.63 m | 6.35 m |
| Peak current | At base | ~¼ up radiator |
| Main lobe angle | 25–30° | 16–18° |
| Gain over real G | ~1.5 dBi | ~2.8 dBi |
| Match needed? | Usually no | Yes (stub/coil) |
Conclusion
Both 1/4-wave and 5/8-wave verticals have their place. But saying they “perform the same near ground” ignores physics. A 5/8-wave, when properly matched, produces lower-angle radiation and a tangible DX edge on the right bands. For 20 m and below, stick to a good 1/4-wave. For 6–12 m, the 5/8-wave is a proven winner.
Mini-FAQ
- Do 1/4 and 5/8 verticals radiate the same near ground? — No. Electrical length changes current taper and lobe angle, which ground losses cannot erase.
- Why does a 5/8-wave need a matching network? — Its natural impedance is ~20–25 Ω. A stub or coil is used to bring it closer to 50 Ω.
- Which bands benefit most from 5/8-wave verticals? — 6 m, 10 m, 12 m, and 4 m, where they provide flatter lobes and more DX gain.
- Should I use a 5/8-wave on 20 m? — Usually not. The physical height is impractical and the gain advantage is negligible over a clean 1/4-wave.
Interested in more technical content? Subscribe to our updates for deep-dive RF articles and lab notes.
Questions or experiences to share? Contact RF.Guru.