VIDEO
I'm Peter G3OJV (waters stanton) and I recently went back to the July 1958 RSGB bulletin that first published Louis Varney's G5RV antenna. The design was conceived in 1946 and, even now—almost 80 years after its conception—it remains one of the most familiar and widely used multiband wire antennas among amateur radio operators. In this article I walk through the original published details, clarify a few misconceptions, and offer practical guidance based on both the historic write-up and modern practice.
Quick snapshot: what Louis Varney intended
Many people today assume the full-size G5RV was intended primarily for 80 m and up. In fact Varney designed it to cover 160 m through 10 m. He conceived the antenna in 1946, circulated details among friends, and finally published the design in 1958. The original article was only about one-and-a-half pages long, but it changed how many amateurs fitted an all-band wire antenna into their gardens.
How the G5RV behaves on each band
The G5RV isn't magic — it's a dipole (often called a doublet) with a carefully chosen top section. The top wire length and the feeder arrangement make it perform well across multiple HF bands:
- 160 m: With the original open-wire feeder shorted together at the feedpoint and fed as a random wire/vertical with a top-loading hat, it can be used on 160 m. This requires the open-wire feeders to be strapped together and fed through an ATU.
- 80 m: Acts as a short dipole. In the original design the point of maximum current is roughly 15 ft down the feeder.
- 40 m: An extended 40 m dipole — a bit longer than a standard half-wave dipole for better bandwidth.
- 20 m: The sweet spot. The top section is three half-waves in phase on 20 m, giving some broadside gain and very good performance.
- 15 m: Slightly extended two full-waves in phase — performs well on 21 MHz.
- 10 m: Functions as two-and-a-half wavelengths in phase — useful on 28 MHz.
Two original versions: balanced feed vs. coax-fed
Varney published two variants:
- Balanced feed (original/full loss-minimised):
- Coax-fed variant:
Open-wire or high-impedance ladder line back to an antenna-matching unit at the shack. Varney pointed out this was the lowest-loss arrangement. Back then the usual open-wire was 600 Ω; today 450 Ω ladder line is a close, practical substitute (allow for velocity factor).
Top section 102 ft, followed by a length of ladder line of roughly 34 ft (a half-wave on 20 m), then transition to coax. In the 1950s 70 Ω coax and 70 Ω balanced feeders were common and gave an acceptable match. Today we mostly use 50 Ω coax — this works too, but introduces a slightly larger mismatch compared with the original 70 Ω approach.
Feeder lengths and the quarter-wave recommendation
Varney recommended the ladder line section be multiples of a quarter-wave (on 20 m) so that the impedance seen at the matching unit is a moderate reactance the tuner can handle. Practically speaking:
- Think of the ladder line length as a multiple of a quarter-wave on the design band (20 m) — this often gives useful impedances at the tuner.
- This isn't absolute. A convenient length that leaves room for trimming is sensible; a slightly longer feed lets you shorten to tune.
- If using 450 Ω ladder line, allow for a velocity factor of ~0.9 so the physical length is slightly shorter than free-space calculations.
Balun, ribbon feeders and coax myths
Varney warned against 300 Ω ribbon feeders because high SWR on them increases loss. He also advised that fitting a balun at the coax-to-ladder junction could increase losses; his original preference was a direct connection. That said, modern practice benefits from addressing common-mode currents:
- I recommend adding a line isolator / common-mode choke at the ladder-to-coax junction to reduce common-mode currents down the coax. Many operators also fit a choke at the rig end for extra suppression.
- Ribbon (300 Ω) ladder is generally less desirable due to higher loss when subjected to substantial SWR on some bands.
Matching units, transceivers and SWR tolerance
The original article didn’t publish exact capacitor or inductor values for the matching unit — in the 1950s many operators built PI-network transmitters and separate matching units and tuned them by trial. A few points to bear in mind:
- Older transmitters with PI networks could tolerate VSWRs of 3:1–5:1 on the feeder; Varney designed the antenna with that era’s equipment in mind.
- Most modern transceivers with built-in ATUs will match a G5RV across its operating bands. Some older days-of-yore transceivers with minimal ATUs may struggle on particular bands.
- If you use coax, expect some variation in loss depending on feedline impedance and SWR. Claims such as "6 dB loss on 30 ft of coax at 10 m" are highly unlikely with realistic impedances and should be treated sceptically unless the claim is backed by measured data.
160 m operation — the original trick
To use the G5RV on 160 m as Varney described, you need the open-wire balanced feeders (the original version). Short the two conductors together at the top so the feed becomes a vertical (or near-vertical) antenna with a large top-loading capacity hat. Feed that assembly through your matching unit. Many stations in the 1950s and 60s did exactly this; it’s less common today but it’s a valid method if you need 160 m capability and have the balanced feeder in place.
Is G5RV special? The top section is the key
The G5RV is fundamentally a doublet. What made it widely successful was Varney’s choice of top-wire length — approximately 102 ft — which places the antenna in a favourable set of resonances (notably the 20 m three-half-wave sweet spot) and makes matching across 80, 40, 20, 15 and 10 workable for many hams.
Half-size G5RV
Varney later commented that a half-size version works well if your garden can’t accommodate 100 ft of wire. The half-size model is simply scaled down and covers 40, 20, 15 and 10 m. Many operators use the half-size G5RV successfully where space is limited.
Practical tips and common-sense rules
- Use 450 Ω ladder line (or good quality open-wire) if you want the lowest loss and to feed the antenna with a balanced tuner at the shack.
- If you must use coax, accept a slight mismatch relative to the original 70 Ω approach. 50 Ω coax will work for most installations.
- Leave the ladder section a little long and trim to tune rather than cutting to an exact theoretical length immediately.
- Do fit a choke/isolator at the ladder-to-coax junction and consider another at the radio to reduce common-mode currents and feedline RF on the rig.
- The matching section needn’t hang perfectly vertical. Having some length (say several metres) dropping vertically before the run angles away is perfectly acceptable.
On modifications and modern variants
There are many modified G5RV variants; one well-known adaptation is the ZS6BKW which aims to improve matching where the coax connects. If you run balanced feed all the way back to the tuner, you really don’t need that modification — the original working principle is sound.
Conclusion
The G5RV’s success is simple: a pragmatic, space-friendly multiband wire that works well with balanced feeders or coax (with some compromises). Varney’s original 102 ft top section and choice of feeders made the antenna flexible across many HF bands, and that design intent—conceived in 1946 and published in 1958—still delivers useful performance today.
If you’re thinking of building one, use good ladder line where possible, allow a bit of feedline for trimming, fit a common-mode choke, and don’t be put off by rumours of huge losses. The G5RV remains a solid, practical choice for many amateur stations.
Thanks for reading — I hope this clears up a few historical points and gives you confidence to try either the full-size or half-size G5RV in your station. 73, Peter G3OJV (waters stanton)
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