Is a Vertical Dipole Suspended Above Ground Balanced or Unbalanced?

A true vertical dipole suspended above ground is balanced in principle. Its vertical orientation does not make it unbalanced. What matters is the feed structure and the RF return path.

If the antenna has two radiating arms and is fed between those two arms with equal and opposite RF currents, it is a balanced dipole. If one side of the feed is the earth, a radial field, a vehicle body, a mast, a metal roof, or the outside of the coax shield, then it is no longer a dipole in the strict feed-system sense. It has become a monopole or ground-referenced vertical system, and that is normally an unbalanced antenna system.

Balanced Does Not Mean Horizontal

A dipole is balanced because the feedpoint is between two antenna halves. In an ideal center-fed dipole, neither terminal is the “ground side.” The two halves are driven in opposite phase and should carry equal-magnitude currents.

That remains true whether the dipole is horizontal, sloping, inverted-V, or vertical.

What Makes a Vertical Antenna Unbalanced?

A vertical antenna becomes unbalanced when it is fed against a reference conductor. That reference conductor can be the earth, buried radials, raised radials, a counterpoise, a vehicle body, a mast, a tower, a PCB ground plane, a metal roof, or the outside of the coax shield.

In that case, one side of the RF system is the vertical radiator and the other side is the ground or counterpoise structure. That is the usual monopole arrangement.

The simple image-theory explanation is familiar: a monopole can be viewed as one half of a dipole working against a conducting plane. The conducting plane, radial field, or earth system supplies the missing RF return structure. In practice, that return structure is rarely perfect, and its losses and geometry become part of the antenna system.

The ITU Terminology: Dipole Reference Versus Short Vertical Reference

The ITU Radio Regulations do not primarily define “balanced” and “unbalanced” antennas in the everyday amateur-radio sense. Instead, they define reference antennas and radiated-power quantities.

That distinction is useful because it separates a dipole reference from a vertical monopole-style reference.

In the 2024 ITU Radio Regulations, antenna gain may be referenced to:

• an isotropic antenna, giving e.i.r.p. context;
• a half-wave dipole isolated in space, giving e.r.p. context;
• a short vertical antenna over a perfectly conducting plane, giving e.m.r.p. context.

The short vertical reference is described as a linear conductor, much shorter than one quarter wavelength, normal to the surface of a perfectly conducting plane. That is a ground-plane-style reference, not a free-space two-arm dipole.

The same section defines effective monopole radiated power, or e.m.r.p., as the product of antenna input power and gain relative to a short vertical antenna in a given direction. In other words, e.m.r.p. is the formal monopole-referenced radiated-power quantity, comparable in concept to e.r.p. being referenced to a half-wave dipole and e.i.r.p. being referenced to an isotropic radiator.

Vertical Dipole Versus Vertical Monopole

The key distinction is simple: a monopole needs an RF return structure outside the radiator. A dipole already has its return structure in the other half of the dipole.

Does Ground Below a Vertical Dipole Unbalance It?

In theory, a center-fed vertical dipole in free space is balanced. In the real world, a vertical dipole is often not perfectly symmetrical because the lower half may be closer to ground, supports, masts, buildings, feedline, trees, or other conductors.

Those surroundings can disturb the current distribution. The lower arm may couple more strongly to earth or nearby objects than the upper arm. The impedance can shift. The radiation pattern can change. The feedline can become involved if it is not isolated properly.

But that does not automatically make the antenna a monopole.

A vertical dipole is still a dipole if the transmitter is feeding two antenna halves. It becomes a monopole if the transmitter is feeding one vertical radiator against ground, radials, a counterpoise, a mast, a vehicle body, or another external RF return structure.

The Feedline Can Change the Practical Answer

A balanced antenna can behave like an unbalanced installation if it is fed poorly. The most common example is a coax-fed dipole without adequate feedpoint choking.

Coaxial cable is an unbalanced transmission line. Inside the coax, the wanted differential-mode current flows on the center conductor and the inside of the shield. Ideally, those currents are equal and opposite, so the external field cancels. But the outside of the coax shield is a separate RF conductor. If the antenna feedpoint does not force equal current into the two dipole arms, some current can flow on the outside of the shield.

That outside-shield current is common-mode current. It can disturb the radiation pattern, change the tuning, alter SWR, increase received noise, and bring RF back into the shack.

How to Feed a Suspended Vertical Dipole Correctly

For a suspended vertical dipole fed with coax, the practical advice is straightforward:

• Use a good 1:1 current balun or common-mode choke at the feedpoint.
• Route the coax away from the antenna at a right angle where possible.
• Avoid running the coax parallel to the lower half of the dipole.
• Keep the lower dipole arm away from lossy soil, metal objects, gutters, fences, and building wiring where possible.
• Verify the installation with an RF current meter if you suspect feedline radiation.

The choke does not make the dipole “balanced” by magic. The dipole structure is already balanced in principle. The choke prevents the coax shield from becoming an unintended third conductor in the antenna system.

Why the Confusion Happens

Many operators are used to seeing vertical antennas as ground-plane antennas. That makes sense because most amateur-radio “verticals” are monopoles: one vertical radiator with radials, a counterpoise, a vehicle mount, a metal roof, or the earth acting as the return path.

But “vertical” describes orientation. It does not define the feed system.

A vertical dipole and a vertical monopole may both radiate vertically polarized signals, but they are not the same antenna. One is a two-arm radiator fed between its two halves. The other is a one-arm radiator fed against a ground or counterpoise system.

Final Answer

A vertical dipole suspended above ground is balanced when it has two real dipole arms and is fed between them.

It is not a monopole merely because it is vertical.

It becomes unbalanced if one side of the antenna system is ground, a radial field, a counterpoise, a mast, a vehicle body, a PCB ground plane, a metal roof, or the outside of the coax shield. That is the monopole or ground-plane case described in ITU-style vertical-monopole terminology.

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