The 20 m EFHW Vertical — Why a Quarter Wave Usually Wins
There’s a persistent idea that every antenna is a compromise. It isn’t. Some antennas are simply engineered correctly for the height and geometry they’re used in, and others… fight physics. On 20 m, the end-fed half-wave (EFHW) used as a vertical is one of those systems that can work, but a properly built ¼-wave vertical with elevated, tuned radials always outperforms it.
This article strips it down to the core: current distribution, voltage distribution, and where your watts get lost.
Where the Current Lives: The Real Difference
A ¼-wave vertical is fed at a current maximum and at a low feedpoint impedance (typically mid-30 Ω). That means:
- Efficient power transfer
- Strong RF current right at the feedpoint
- A simple, low-loss match
- No dependence on coax length to “complete the antenna”
Add a few elevated, tuned radials and you’ve created a clean, predictable return path. SWR and pattern become stable and repeatable, and low-angle radiation is easy.
The EFHW Vertical: High Voltage in the Worst Possible Place
A 20 m EFHW is about 10.6 m long and presents a feedpoint that is:
- A voltage maximum
- A current minimum
- A very high impedance
That forces the use of a high-ratio transformer. Even a good one wastes a bit of power as heat. And because the transformer sits at ground level, you’ve placed a high-voltage node right in the soil’s near‐field — which increases capacitive coupling and loss. (Soil is a terrible dielectric.)
And “end-fed” is never really end-fed. You always need a return path. Without a proper counterpoise and choke, the system grabs the nearest metal:
- Coax shield
- Mast
- Station equipment
- Anything bonded to the matchbox
This is why EFHW verticals often feel unstable — move the coax, change the length, or shift the matchbox by 50 cm, and the SWR and pattern can change noticeably.
Height: The Hidden Killer
The 20 m ¼-wave radiator is only 5.3 m long — easy to elevate, and easy to keep the main current region away from lossy ground.
The EFHW needs the feedpoint several metres up (8 m) to stop the high-voltage zone from coupling into earth and the feedline. Most low installations never achieve this, which costs a couple of real-world dB.
So Which One Should You Build?
If you can build a ¼-wave vertical:
- ~5.3 m radiator
- 3-4 elevated radials of similar length
- 1:1 choke at the feedpoint
Simple, efficient, low-angle, and stable.
If you must use a 20 m EFHW vertical:
- Raise the feedpoint as high as possible (6–8 m)
- Add a short counterpoise or short radials
- Add a high-impedance 1:1 choke at the transformer
- Use a properly built transformer that stays cool at your power level
- Expect installation sensitivity
A well-installed EFHW works. But on 20 m, the ¼-wave vertical is almost always the cleaner, stronger, and more predictable performer.
Mini-FAQ
- Is an EFHW always lossy? Not always — but as a vertical on 20 m, the low feedpoint and high voltage near ground increase loss unless the system is elevated.
- Why do radials improve a ¼-wave so much? They give the return current a clean, low-loss path instead of letting it wander through the coax and the station.
- Is a 49:1 transformer inefficient? Any high-ratio transformer adds loss. A ¼-wave vertical avoids the transformer entirely.
- Can an EFHW beat a ¼-wave? Only if installed high with proper counterpoise and choking. Most installations don’t do that.
Interested in more technical content? Subscribe to our updates for deep-dive RF articles and lab notes.
https://shop.rf.guru/pages/subscribe
Questions or experiences to share? Feel free to contact RF.Guru.
https://shop.rf.guru/pages/contact