G5RV Antenna: What It Does, What It Doesn’t, How to Use It

Few antennas generate as much argument as the G5RV antenna. Some operators call it the ideal garden multiband wire, others call it an overrated compromise that needs a tuner everywhere except one band. Both camps are partly right. The G5RV is a centre-fed dipole with a short length of ladder line as a matching section, and it has been working contacts since the 1940s because it is simple, fits in many gardens and is cheap to build. It also has limits that are easy to miss if you only read the advertising.

This guide explains how the design works, uses the dimensions from published sources, shows what to expect on each band and gives practical advice on the balun, the tuner and the installation. The explanation of the design draws on the inventor’s own article, which is reproduced online, and on the general encyclopedia entry for the antenna.

Where the G5RV Comes From

The antenna was invented by Louis Varney, G5RV, in 1946, according to the encyclopedia entry, and it became particularly popular in the United States. It can be erected as a horizontal dipole, a sloper or an inverted V, and with an antenna tuner it can operate on all the HF amateur bands from 3.5 to 30 MHz. In Varney’s own description of the antenna it is a multiband, centre-fed antenna designed with dimensions that fit into gardens and other open spaces that can take a reasonably straight run of 31.1 metres (102 feet) for the full-size version.

That origin matters. The G5RV was never presented as the best antenna for any one band. It was designed as a way to cover many bands with one wire and one feeder where space is limited, and it should be judged on that basis.

Dimensions and Construction

The full-size antenna has a flat-top of 31.1 metres, which is two arms of about 15.55 metres each. Below the centre insulator hangs a matching section of balanced line. The encyclopedia entry gives its length as 8.84 metres (29 feet) if it is 300 ohm line or 10.36 metres (34 feet) if it is 450 ohm line. Varney’s article quotes 10.36 metres (34 feet) for the open-wire or ladder-line version. The design centre frequency for the full-size antenna is 14.150 MHz. A half-size version halves both the flat-top and the matching section, and Varney describes it as efficient from 40 to 10 metres.

Varney advised choosing the matching-section line for the lowest loss, which means ladder line rather than coax. He suggests copper or protected steel wire with a UV-resistant covering so that the wire does not oxidise or rust, and he reminds builders to check the fixings and insulators. Many commercial versions are sold with different feeder types, so check which one you are buying.

How the Matching Section Works

Varney is explicit that, unlike most multiband antennas, the full-size G5RV was not designed as a half-wave dipole on its lowest frequency. It was designed as a centre-fed long wire that is three half wavelengths long on 20 metres, with the 10.36 metre section acting as a 1:1 impedance transformer on that band. On 20 metres the radiation resistance at the centre of a three-half-wave wire at a suitable height is about 90 ohms, so a 75 to 80 ohm feeder sees a nearly resistive load and the standing wave ratio is very close to 1:1. Even a 50 ohm coaxial feeder gives only about 1.8:1.

On the other bands the matching section does not transform anything cleanly. It becomes a make-up section that carries the part of the standing wave that cannot be accommodated on the flat-top. The antenna and the section then present a reactive load to the feeder, so a tuner is needed. Varney stresses that the type of tuner matters: an unbalanced-to-balanced one if you feed twin-wire line, or an unbalanced-to-unbalanced one if the feeder is coax.

What to Expect Band by Band

Because the antenna has no traps or ferrite loading, its electrical length grows with frequency. Varney notes that this lowers the main lobes of the vertical pattern as the frequency rises, which is why a G5RV tends to have useful DX angles from 20 metres upward. He also warns that theoretical patterns assume free space above perfect ground, so real-world patterns will differ because of nearby wires, gutters, masts and trees and the local ground conductivity. Do not be surprised if a contact comes from a direction where the theory shows a null.

The 160 Metre Problem

The 160 metre case deserves its own section because it is where the most expensive mistakes are made. Varney’s article says that on this band the unmodified antenna does not work at all, at least when transmitting. The impedance is very high and reactive, a tuner that manages to load it will give an extremely high SWR on the feeder, and most of the transmitter’s power turns into heat in the feeder and the tuner inductors. The article warns against driving an antenna that is too short in this way, and points out that it can damage transmitter output stages and the tuner, for example by cracking toroid cores or melting the forms in roller inductors.

The article suggests modelling modifications with a program such as EZNEC and notes that even optimised arrangements may give modest efficiency. If top-band performance is a priority, it is better to use a purpose-built antenna. Our guide to 160 metre DXing covers the options in detail.

Balun, Choke and Feeder Choices

The point where the balanced matching section meets unbalanced coax is the weakest spot of the system. The encyclopedia entry notes that soldering the ladder line straight to coax is not good practice, because it can cause high current on the outside of the coax braid, which causes RF interference and distorts the antenna’s polarisation and gain. Varney recommended a balanced matching network at the end of the ladder line. The entry also describes using a 4:1 voltage balun to connect coax to the ladder line and a 1:1 current balun between the coax and the transmitter, and says that a current balun not only prevents interference but can reduce receive noise. For operation without any balun, it recommends at least 20 metres (66 feet) of coax.

In practice, many operators use a 1:1 current balun or a common-mode choke where the ladder line meets the coax, and a second choke near the station. Our articles on baluns and ununs and common-mode chokes explain how to choose them. If you feed the antenna with open-wire line all the way into a balanced tuner, you avoid the transition, but you must route the line away from metal and keep it clear of other wiring. Our doublet antenna guide covers that approach.

Choosing a Tuner

With a G5RV, the tuner is part of the antenna system. Pick one that can handle a reactive load with a high SWR at the point where it is connected, and check that it is rated for the power you will use. Varney points out that modern transmitters with ALC systems protect themselves when the load has a higher SWR than about 2:1, which is why a tuner is essential on most bands. Read our guide on choosing an external antenna tuner before you buy, and remember that a tuner hides the mismatch from the radio but does not remove the losses in the feeder.

Height, Layout and Variants

• Height. The encyclopedia entry says the height above ground should be at least half of the longest wavelength used. In reality few gardens allow that on 80 metres, so expect a high takeoff angle there, which suits regional contacts rather than DX.
• Inverted V. Varney says up to one-sixth of the total length at each end can be dropped vertically or bent without significant loss of radiation efficiency, which makes the antenna adaptable to small plots.
• Surroundings. Keep the ladder line away from gutters, wires and metal, since they change the pattern and can pick up noise.
• Variants. The entry mentions the ZS6BKW and W0BTU designs, which can match several more bands between 3.5 and 28 MHz without a tuner. They have different dimensions, so do not mix them up with the G5RV.

For a wider view of how height affects the radiation angle on any wire antenna, read antenna height and takeoff angle.

Putting One Up and Checking It

Treat a G5RV like any other multiband wire: build it, then measure it. Hoist the flat-top as high and as straight as your supports allow, and bring the ladder line away from the centre at right angles for as far as you can before it turns toward the house. Let it hang free of the wall on standoffs or a non-metallic support. Once the antenna is up, sweep the SWR on each band with an antenna analyser and write the results down, both at the tuner input and with the tuner bypassed. A small vector analyser makes this easy and also shows the reactance, which tells you whether the mismatch is mostly high impedance, low impedance or reactive. Repeat the sweep after rain, because wet insulation and ladder line can shift the readings.

Then compare it on the air. Listen to the same stations on the G5RV and on any other antenna you have, and make a few contacts to check the signal reports. Use a tuner with a good indicator, keep the power modest while you learn how it loads on each band and watch the tuner for heat or arcing. If a band loads poorly, a small change in the length of the feeder or the flat-top can help, but a long run of coax between the tuner and the shack can add more loss than any adjustment will recover.

How It Compares With Other Multiband Wires

The G5RV sits between the simple doublet and the trap dipole. A doublet fed with ladder line all the way to a balanced tuner can be more efficient on some bands, because it has less coax in the system, but it needs a balanced tuner and a clean route into the shack. A trap dipole matches a few bands without a tuner but covers fewer of them and has losses in the traps. An off-center-fed dipole is easy to feed with coax but needs a good current balun or choke. The G5RV, with its fixed 102 foot flat-top and short ladder-line section, is a compromise that suits operators who want to cover everything from 80 to 10 metres with one wire.

Common Mistakes

• Expecting a perfect SWR everywhere. Only 20 metres comes close without a tuner.
• Feeding the ladder line directly into 50 ohm coax without a balun or choke. This sends current onto the braid.
• Running the ladder line along a metal wall or pipe. It unbalances the system.
• Trying to use it on 160 metres unchanged. The efficiency is close to zero.
• Judging it on one test. Compare it against another antenna on real signals before deciding.

The Bottom Line

The G5RV remains a sensible choice for operators who have about 31 metres of space, a good tuner and a balun or choke at the transition point, and who want to be active on many HF bands without building anything complicated. It performs best from 20 metres upward, works adequately on 40 and 80 metres, and was never meant for 160 metres. Know what its matching section does, use it with realistic expectations and you will get a lot of use out of a very simple wire.

Frequently Asked Questions

How long is a G5RV antenna?

The full-size flat-top is 31.1 metres (102 feet). The half-size version is half of that. The ladder-line matching section is 10.36 metres (34 feet) for 450 ohm line in the full-size version.

Do I need an antenna tuner with a G5RV?

Yes, on all bands except around 14 MHz, where the design presents a near-resistive load. Use a tuner suited to the feeder type, balanced or unbalanced.

Does the G5RV work on 160 metres?

Not without modification. The designer’s own article says the unmodified antenna does not work at all on that band when transmitting, because the flat-top is far too short.

Where does the balun go?

The encyclopedia entry describes a 4:1 voltage balun or a balanced matching network at the ladder-line end, plus a 1:1 current balun near the transmitter. Many operators use a choke at the transition.

Is the G5RV a good DX antenna?

From 20 metres upward the designer says the vertical pattern lowers as frequency increases, which suits DX. Height, surroundings and ground still decide how it performs in your location.

What are the ZS6BKW and W0BTU antennas?

They are variants of the same idea with different dimensions. The entry says they can match several more bands between 3.5 and 28 MHz without a tuner.