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An aerial made of thin air: the 30 MHz signal sent down a laser beam

Qurexa Editorial Team12 October 20266 min read 0 0
An aerial made of thin air: the 30 MHz signal sent down a laser beam

What happened

Engineers in the United States have transmitted a radio signal using an antenna made of air. The work came out of North Carolina State University and was announced on 9 October 2026. It is published, open access, in the IEEE Journal of Microwaves. The authors are Prya Darshni, Arthur Dogariu and Professor Paul Franzon. An antenna is normally a piece of metal. It has to be, because radio signals travel along conducting material. The length of that metal decides which frequencies the antenna handles well, and pointing it somewhere else usually means physically moving it. The NC State team did something different. They fired a laser into the air and used it to strip electrons from a narrow channel of air molecules. That turns the channel into plasma, and plasma conducts electricity. So the glowing column of air became the antenna. Feeding power into a column of air is the next problem, and they solved it without touching it. A metal ring sits around the plasma and acts as a capacitor. A radio frequency generator drives the signal through that ring, and the energy crosses into the plasma without any physical connection. With that setup, they transmitted at 30 megahertz, in the very high frequency band. Prya Darshni, a PhD student at NC State and the paper's first author, said "it is the first time anyone has ever demonstrated that plasma-filament antennas can work".

Why this matters

The appeal is that an antenna made of air can change shape. With a metal antenna, the hardware decides the frequency. With this approach, the laser decides. As Darshni explained: "By controlling the parameters of the laser, you can control the characteristics of the plasma filament." Change the laser settings and you change the antenna's length. Move the laser and you change where the antenna points. That removes moving parts. Anything with a motor in it is something that can seize, wear out or need servicing, and that matters most in places nobody can reach to fix it. Which brings in the space angle. Professor Franzon noted that "in low earth orbit, there is sufficient air to form a plasma". A satellite that could form an antenna out of the thin atmosphere around it, rather than carrying and deploying a metal one, would be a genuinely different kind of spacecraft. There is a more down-to-earth reading, too. Radio in the VHF band is used for aircraft communication, marine radio, emergency services and broadcasting. Antenna design is one of those quiet engineering constraints that shapes what all those services can do.

What the evidence actually says

This is an early proof of concept, and it is important to say what has not been shown. The team demonstrated transmission. They have not yet tested whether the plasma antenna can receive signals, and they have not tested it across a broad range of frequencies. Both of those would be essential for most real uses. The paper reports one measured figure, the 30 MHz transmission frequency. It does not report laser power, beam diameter or antenna efficiency. Without efficiency numbers it is impossible to say how this compares with a metal antenna in practice, and efficiency is usually where clever ideas meet hard limits. The space application is openly speculative. Whether it would work under real space conditions needs further research, and the researchers say so themselves. It is also worth noting the obvious: this requires a laser. A system that needs a laser running continuously to maintain its antenna is carrying a power budget that a strip of metal does not. For some applications that trade will be worth it. For most, it will not. So the honest position is that a real, measured, first-of-its-kind result has been achieved, and that a great deal of work stands between it and anything you would deploy.

Practical advice

There is nothing to do with this one, and no product to wait for. What it is good for is a reminder about how to read technology news. This story has a striking image attached to it, a glowing column of air described in several outlets as lightsaber-like. That image is doing a lot of the work in how the story travels. The actual result underneath it is narrower and more careful: one frequency, transmission only, no efficiency data, open questions about receiving. Neither version is wrong. But the gap between them is where most misunderstanding about science and technology lives. A useful habit is to look for three things in any research story. What exactly did they measure? What did they not test? And who is saying it is early, in their own words? In this case, all three are available and easy to find, because the paper is open access. Anyone can read it. That is worth knowing in itself. A growing share of publicly funded research is published open access, which means you are not dependent on someone else's summary. If a claim matters to you, the original is often one click away.

What to know

Researchers at North Carolina State University have transmitted a radio signal at 30 MHz using an antenna made of ionised air rather than metal. A laser creates a narrow plasma channel, and a metal ring acts as a capacitor to feed energy into it without any physical contact. The work was published open access in the IEEE Journal of Microwaves and announced on 9 October 2026. The advantage is adaptability: laser settings can change the antenna's length and direction with no moving parts. Possible uses include satellites in low Earth orbit, where there is enough air to form a plasma. The limits are substantial. Only transmission has been demonstrated, not reception. Broadband operation is untested. The paper reports no efficiency figures, and the space application is speculative. The team describes it as an early proof of concept. Sources: North Carolina State University / ScienceDaily, "Scientists create a lightsaber-like laser antenna that transmits radio waves", 9 October 2026, https://www.sciencedaily.com/releases/2026/10/261008005239.htm ; Prya Darshni, Arthur Dogariu and Paul D. Franzon, "Laser-Induced-Plasma-Filament Antenna Transmitting 30 MHz VHF", IEEE Journal of Microwaves, 2026, 6(5): 1174, DOI 10.1109/JMW.2026.3722433 This article is for general information and does not replace advice from a doctor, pharmacist or other qualified healthcare professional.

#engineering#antennas#plasma#radio#space technology#research

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