Building a Vertical Antenna: Ground-Mounted and Elevated Radial Designs

Verticals are the antenna of compromise — and I mean that as a compliment. When you can't put up a horizontal dipole at 50 feet (and most of us can't), a vertical gives you competitive performance in a package that's less visible, requires less horizontal space, and radiates at low angles for DX without needing height.

I've built five verticals over the past four years. Ground-mounted quarter-waves with radial fields, elevated verticals with four radials, and one disastrous experiment with a rain gutter that I don't talk about. Here's what I've learned that the textbooks gloss over.

The Two Approaches

Ground-mounted vertical: Base at ground level, radial wires laid on or in the ground. Requires many radials (16-32+) for efficiency. Classic design.

Elevated vertical: Base raised 8-15 feet above ground on a mast or support. Requires only 2-4 radials (resonant, elevated). Less ground loss.

Both work. The choice depends on your situation, not which is "better" in some abstract sense.

Ground-Mounted: The Quarter-Wave Vertical

Materials

• Aluminum tubing: 1.25" to 0.5" telescoping sections, total length = quarter wavelength at design frequency
• Ground rod or mounting plate
• Radial wire: #14 or #16 bare copper or insulated, lots of it
• SO-239 chassis mount connector
• Ground strap or clamp
• Hose clamps for tubing joints

Quarter-wave length calculator

Length (feet) = 234 / frequency (MHz)

• 40m (7.15 MHz): 32.7 feet
• 20m (14.15 MHz): 16.5 feet
• 15m (21.2 MHz): 11.0 feet
• 10m (28.4 MHz): 8.2 feet

The Radial System (This Is Where People Fail)

A ground-mounted vertical without radials is a dummy load. The ground is the other half of the antenna. If your ground system is lossy, you're heating dirt instead of radiating RF.

How many radials?

• 4 radials: works, but you're losing 3-6 dB in ground resistance. Painful.
• 16 radials: significant improvement. Maybe 1-2 dB of ground loss.
• 32 radials: approaching diminishing returns. About 1 dB loss.
• 60+ radials: the textbook ideal. Less than 0.5 dB ground loss.
• 120 radials: N7CL measured this. Barely better than 60.

For most home stations, 32 radials is the sweet spot between effort and performance. Each radial should be at least 0.25 wavelength long (same as the vertical element). Lay them on the ground in a fan pattern. They don't need to be buried — just pinned down with landscape staples. Grass grows over them in a month.

I laid 32 radials for my 20m vertical in one afternoon. Used a bulk spool of #14 THHN from Home Depot (~$50 for 500 feet). Cut each one to 17 feet, soldered all ends to a ring terminal, bolted the ring to my ground plate. Took about 3 hours including lunch. Not glamorous work. But the antenna went from an SWR of 2.5:1 with 4 radials to 1.3:1 with 32.

Assembly

1. Drive ground rod or set base plate where the antenna will stand
2. Mount SO-239 connector at base — center pin connects to vertical element, shell connects to radial system
3. Telescope aluminum sections together, secure with hose clamps + self-tapping screws through overlap
4. Raise vertical and attach base to mounting plate/ground rod
5. Spread radials evenly around base, connect all to SO-239 shell/ground plate
6. Check SWR — trim vertical length for resonance

Tuning

Start with the vertical element about 3% longer than calculated. Check SWR at design frequency.

• SWR dip above your target frequency → antenna is too short, extend slightly
• SWR dip below your target frequency → antenna is too long, trim from the top

Adjust in 1-inch increments. Recheck. The resonant point should have SWR under 1.5:1 if your radial system is adequate.

If SWR is high everywhere (above 2.5:1 at all frequencies), your problem is almost certainly insufficient radials or a bad connection at the feedpoint. Not the element length.

Elevated Vertical: The Better Option for Most

Here's what surprised me: an elevated vertical with only 4 radials can match or outperform a ground-mounted vertical with 32 radials. The reason is simple — elevated radials carry current in free space instead of losing it to ground resistance.

The Design

• Same quarter-wave element as ground-mounted
• Base elevated 8-15 feet above ground (on a push-up mast, fence post, tree, anything)
• 4 resonant radials, same length as the vertical element, angled slightly below horizontal (30-45° droop is fine)
• That's it. Seriously.

Why It Works Better With Fewer Radials

Ground-mounted radials lie in or on lossy earth. Current flowing through them induces currents in the ground beneath. Energy is lost as heat. You need dozens of radials to create an effective "screen" that prevents ground currents.

Elevated radials are in the air. Current flows in copper, not dirt. Four elevated radials provide the necessary counterpoise without ground loss. NEC modeling confirms it, and I've measured it: my 4-radial elevated 20m vertical outperformed my previous 16-radial ground-mounted version by about 1.5 dB on received signals from DX stations.

Installation

I use a military surplus fiberglass mast (about $40 from fair Radio Sales or surplus dealers) as the support. The vertical element mounts on top, radials attach at the feedpoint and droop at roughly 45°.

Feedpoint height: 10 feet works. High enough that radials clear heads, low enough to manage easily. The higher the feedpoint, the slightly better the performance — but the returns diminish fast above 0.1 wavelength height.

Practical Radial Notes

• Use insulated wire for elevated radials — prevent accidental shorts if they swing and touch something
• Radials don't need to be perfectly symmetric. Two toward the house, two toward the yard? Fine. Performance difference is negligible.
• Slightly drooped radials actually lower the feedpoint impedance closer to 50 ohms (horizontal radials give about 36 ohms, drooped gives 42-50 ohms). Less matching needed.
• Secure radial ends so they don't swing in wind and fatigue-break at the feedpoint connection

Multiband Options

Trap vertical: Add LC traps at specific points to create resonances on multiple bands. The Hustler 4-BTV and Butternut HF9V use this approach. Works, but traps add loss and narrow bandwidth on each band.

Linked vertical: Use removable links (alligator clips or Anderson connectors) to change electrical length. Simple, low-loss, but manual band changes.

Fan vertical: Multiple quarter-wave elements of different lengths, all fed from the same point. Each element resonates on its band while being nearly invisible to the others. Wider at the top but very effective.

End-loading: Add a capacity hat or horizontal wire at the top to electrically lengthen a physically short element. Useful when you can't fit a full quarter-wave for lower bands.

My current setup is a linked elevated vertical for 40m and 20m. Full quarter-wave for each band, switch with a alligator clip 16 feet up the element. Lazy? Yes. Works perfectly? Also yes.

Common Vertical Antenna Mistakes

Running coax along the ground near radials. The coax shield becomes part of the radial system, and RF flows back down the outside of the shield into your shack. Use a choke balun (or ugly balun — 10 turns of coax on a 6" form) at the feedpoint.

Assuming SWR = performance. Your vertical can show 1.1:1 SWR with four radials. That doesn't mean it's radiating well. It might be a perfect match to a lossy ground system — converting most of your power to heat. SWR tells you about match, not efficiency.

Forgetting the choke. Seriously. I see this constantly. No feedline choke = common-mode current = RFI in the shack, pattern distortion, inaccurate SWR readings. A $15 ferrite choke (snap-on type 31 or wound on a FT240-31 toroid) fixes it.

Cutting the element to exact calculated length. Always start long and trim. Cutting is irreversible. Adding length requires a splice or new tubing. Ask me how I know. (Twice.)

Realistic Performance

A properly built vertical with adequate radials (ground-mounted 32+ or elevated 4+) will:

• Perform within 1-2 dB of a dipole at 40+ feet for DX (low-angle radiation)
• Beat a low dipole (under 30 feet) for DX work on 20m and higher bands
• Lose to a high dipole for NVIS/regional contacts
• Be noisier on receive (verticals pick up more man-made noise because they "see" more of the horizon)
• Work well for casual DXing, contests, and daily HF operation

They're not magic. They're not junk. They're a solid option when horizontal antennas at proper height aren't feasible. Build one right and you'll work the world from your backyard.