Part of our Building Your First Ham Radio Station guide.
Verticals are popular for a good reason. They take up little space, they radiate at low angles that are great for DX, and they do not need a tall tower or big trees. But there is a catch that trips up a lot of newcomers. A quarter-wave vertical is only half of an antenna. The other half is the ground system, and if you skimp on it you leave a surprising amount of performance on the table.
Why a vertical needs radials at all
A quarter-wave vertical works against a ground plane. Think of a classic dipole cut for a band. It has two halves, each a quarter wavelength long, and both halves radiate. A ground-mounted vertical replaces the lower half of that dipole with the earth and a set of radials. The radials give the return currents somewhere to flow and effectively act as the missing bottom half of the antenna.
Without a decent ground system, the antenna still radiates, but the earth right under it is a lossy conductor. Every bit of current that flows through that soil instead of through a good radial turns into heat rather than radio waves. That loss shows up as watts that never leave your antenna.
Ground loss is the real enemy
Here is the part that surprises people. Adding radials often does not change your SWR much, so it is easy to think they do not matter. But SWR only tells you how well power is being accepted by the antenna system, not how much of it is being radiated versus wasted.
A vertical over poor ground with just a couple of radials can show a lovely 1.2 to 1 SWR while quietly throwing away a large fraction of your power as ground loss. The antenna looks happy on the meter and performs poorly on the air. This is why chasing a perfect SWR reading without thinking about the ground system is a trap.
More radials, less loss
The general rule is that more radials mean less ground loss and more of your power actually radiating. The classic reference point is a system of 120 quarter-wave radials, which is what broadcast stations use to approach a near-perfect ground plane. You do not need anything close to that, but the trend is worth understanding:
- A handful of radials (say 4) is a real improvement over none and gets a raised or elevated vertical working reasonably well.
- Going from 4 to 16 ground-mounted radials brings a noticeable reduction in loss.
- The gains keep coming as you add more, but with diminishing returns. Going from 16 to 32 helps less than going from 4 to 16, and beyond about 30 to 60 radials the improvement per radial gets small for most amateur setups.
For a lot of hams, something in the range of 16 to 32 radials hits a sweet spot of good performance without an unreasonable amount of wire and work.
Ground-mounted versus elevated radials
There are two common approaches, and they behave differently.
Ground-mounted radials lie on or just under the surface. Because they sit against lossy earth, you want a lot of them to do a good job. The good news is they do not need to be a precise length. You can lay down many random-length wires and the system still works well, since their job is mostly to shield the antenna from the lossy soil.
Elevated radials are raised off the ground and tuned to roughly a quarter wavelength. Here is the interesting part. Because they are up in the air and away from the lossy dirt, you can get excellent results with just a few of them. As few as two to four properly tuned elevated radials can rival a much larger ground-mounted field. This is why so many portable and vertical designs use a small number of counterpoise wires or radials elevated off the ground.
The practical takeaway
If you run a ground-mounted vertical, put down as many radials as you reasonably can. They do not have to be perfectly straight, equal length, or precisely tuned. Quantity matters more than precision here. If you are working with an elevated or raised vertical, a smaller number of tuned radials will do the job nicely.
Either way, remember that your ground system is not an afterthought. It is half the antenna. Spend your effort there and your vertical will reward you with signals that actually get out.