Why We Love Doublets (And Why the G5RV and Its Siblings Are a House of Cards Made of Apple Cake)

There is a deep and enduring love among seasoned radio amateurs for the humble doublet antenna. Suspended high and fed with open wire line straight into a good tuner system, the doublet is simple, elegant, and forgiving. It's the kind of antenna that, once installed properly, becomes a reliable workhorse. In contrast, the G5RV and its many variants are often more trouble than they’re worth. Sure, on paper they promise multiband capability without fuss. But in practice? They're a house of cards held together by theoretical idealism — and they crumble like a poorly impeded apple cake at the first sign of real-world complexity.

Let’s talk about why.

The Doublet: Unapologetically Honest

A doublet is a center-fed dipole of any length, typically between 30 and 80 meters, fed with open wire (we use 600 ohm). There is no built-in expectation that it will be resonant on any band — and that’s a feature, not a bug. The open wire line presents low loss even under high SWR, and a quality tuner system (especially one placed near the feedpoint) handles the transformation.

What makes the doublet so attractive is its brutal honesty. It makes no secret of its needs. It says, "I’ll work across many bands — but give me height, give me balance, and give me a good tuner."

The G5RV: A Misunderstood Trickster

The G5RV, created by Louis Varney (G5RV), is a 31 meter dipole with a specific length of 300-ohm twin-lead (or 450-ohm ladder line) meant to act as a sort of frequency-dependent impedance transformer. It was originally designed for 20 meters — and only 20 meters. Yet over the years, it’s been stretched into claims of multiband magic.

The system relies on a delicate interaction between:

  • The antenna’s height above ground (which changes the current distribution)
  • The specific length and impedance of the feedline
  • The coaxial feed and any matching network

This is a precarious, carefully tuned game. When everything is perfect — height, environment, feedline length, ground conductivity — it can provide decent performance on multiple bands. But when conditions change? Rain, wind, seasonal moisture, or even leaves brushing the feedline can shift the impedance enough to detune the whole system. And suddenly your G5RV turns into an obstinate, mismatched wire that no tuner can coax back to life.

Apple Cake and Other Siblings

Many variants of the G5RV have sprung up over the years:

  • ZS6BKW: A re-optimized version for better multiband coverage, especially on 10 and 17 meters.
  • W5GI "Mystery Antenna": A G5RV-style system with phasing lines to emulate gain patterns — another cake balanced on toothpicks.
  • G0FAH Optimized G5RV: Another attempt to tweak the feedline length for better matching.

Each one tries to mitigate the G5RV’s instability by shifting the game board, but they still rely on a complex interplay of environment, height, and coaxial interaction. They are intricate solutions to a problem that doesn’t exist if you just run a doublet and feed it properly.

Why the Doublet Wins

  • Consistent: Once up, it doesn’t care much about rain, wind, or leaves.
  • Efficient: Open wire line has negligible loss, even under high SWR.
  • Tunable: With a proper tuner system, any band is fair game.
  • Honest: Doesn’t pretend to be resonant. It just works — with help.

Final Thoughts

The G5RV and its descendants are clever but fragile. They promise ease, but often deliver frustration. A doublet, by comparison, asks for a bit more up front — but rewards you with years of dependable performance.

So next time you’re tempted by the apple cake of multiband magic, remember: sometimes the simplest solution, fed right and tuned well, is the sweetest.

Stick with the doublet. Leave the house of cards to the magicians.

Written by Joeri Van Dooren, ON6URE – RF, electronics and software engineer, complex platform and antenna designer. Founder of RF.Guru. An expert in active and passive antennas, high-power RF transformers, and custom RF solutions, he has also engineered telecom and broadcast hardware, including set-top boxes, transcoders, and E1/T1 switchboards. His expertise spans high-power RF, embedded systems, digital signal processing, and complex software platforms, driving innovation in both amateur and professional communications industries.