A tethered drone hides its link, not its radio

I spent my Army career in counter-IED and electronic warfare. A lot of that job is geometry: who can hear whom, from where, and what that costs you. So when a test report says a system "bypassed signal jamming," my first question is which signal, and my second is who else can now hear it.

What the Army actually tested

The Army's own account is short and clear. From 27 July to 7 August 2026, soldiers and capability developers at the Maneuver Battle Lab at Fort Benning, Georgia, assessed tethered unmanned aircraft systems (Te-UAS) at McKenna Field Landing Site. The lab worked with several requirements offices and with Product Lead Strategic Spectrum Warfare, and it put "two commercial Te-UAS capability surrogates through static, on-the-move and emergency scenarios." The drones climbed to "operationally relevant altitudes," the lab timed ascent and retraction, and it tested a "follow-mode" in which the drone tracked above an Infantry Squad Vehicle-Utility as it moved.

Then the sentence the coverage ran with:

Moving between designated target reference points, operators bounced communications over terrain obstacles, bypassed signal jamming and spotted targets from safe distances.

The Army also explains the mechanism. Unlike a free-flying drone, the tethered one "receives continuous power and exchanges data through its physical tether." One participant compared the setup to "a very high tower." And the lab is candid about what kind of event this was. "The Maneuver Battle Lab's mission is experimentation," said Tollie Strode Jr., the government oversight lead. The results go into a final report that helps decide whether the Army buys the technology at all.

Trade coverage turned that into a jamming story. Army Recognition's headline says the Army "tests tethered drones on moving Infantry Squad Vehicles to counter signal jamming." Defence Blog wrote that the goal was to help units "see farther and keep radios working even when the terrain or enemy jamming gets in the way." At least one outlet's headline went further and called it a drone that is "invisible" to electronic warfare systems.

What the cable really protects

Start with the part that is right. A normal small drone talks to its operator over radio: commands up, telemetry and video down. That radio link is the thing a jammer attacks. Put the commands and the video on a wire and there is nothing in the air for the jammer to hit. I have written before about fiber-optic drones, which use the same trick for the same reason. For a tethered drone doing surveillance, with its camera feed running down the cable, the claim holds up: the aircraft's own link is out of the jammer's reach.

Army Recognition's longer analysis says this well, noting that a tether can carry commands and sensor data "directly between a drone and its ground station, reducing RF dependence." Reducing, not eliminating. That word matters once you look at the other mission in the test.

A relay is a transmitter, on purpose

"Bounced communications over terrain obstacles" means the drone carried a radio relay. The unit's radios could not reach each other past a hill or a tree line, so a radio went up on the drone, where it could see both sides. That is exactly why the Army wants this. It is also a transmitter, lifted as high as the tether allows, radiating the unit's traffic.

The cable does nothing for that radio. The relay has to send and receive over the air, or it isn't relaying. So the jamming the cable "bypassed" is the jamming aimed at the drone's control link. The network the drone is relaying is still a radio network, and now its busiest node sits tens of meters in the air.

The geometry cuts both ways

Here is the one equation worth knowing. The Navy's Electronic Warfare and Radar Systems Engineering Handbook gives the standard rule of thumb for line-of-sight range over the curve of the earth:

R_NM = 1.23 (√h_radar + √h_target), with h in feet

The handbook writes it for radar, and it applies to any line-of-sight radio link, because it is just the horizon with the standard allowance for how the atmosphere bends radio waves. The handbook explains that it assumes an Earth radius "4/3 times the actual radius" to account for that bending.

Run the numbers for two antennas on vehicles, each about 3 meters (10 feet) up. The horizon between them is about 7.7 nautical miles, roughly 14 km, over perfectly smooth ground. Now lift one antenna on a tether. My arithmetic with the handbook's formula:

• Relay at 50 m (164 ft) to a 3 m antenna: about 19.6 nautical miles, roughly 36 km.
• Relay at 100 m (328 ft) to a 3 m antenna: about 26.1 nautical miles, roughly 48 km.

Those are horizon limits, not guaranteed ranges. Real radios run out of power, and real terrain blocks paths long before the horizon does. But the point doesn't depend on the exact number. The formula doesn't know which antenna belongs to you. If your squad 20 km away can now hear the relay because it is high enough to clear the hill, so can an enemy intercept receiver 20 km away in the other direction. An enemy jammer gets the same geometry in reverse: it can reach the relay's receiver from farther out than it could reach a radio parked behind a berm. Elevation buys range for everyone on the channel, friend or not.

This is not a knock on relays. Every retransmission site trades exposure for reach, and sometimes the reach is worth it. The problem is only the framing. A tethered relay does not make a unit harder to hear. For most of the enemy's receivers, it makes the unit easier to hear.

What Army radio doctrine says about this

None of this is new to the Signal Corps. The Army's radio techniques manual, ATP 6-02.53, Techniques for Tactical Radio Operations (the January 2016 edition I read), spends a chapter on electronic protection, and much of it is about staying hard to find. Three passages stand out next to a relay hovering over a vehicle.

On terrain: "When possible, utilize terrain features to mask friendly communication from enemy positions." A relay at 100 meters is the opposite of terrain masking; its whole job is to clear the terrain.

On where emitters sit: commanders are told to "disperse and position antennas and emitters at the maximum remote distance and terrain dependent from the CP to ensure that not all of a unit's transmissions are coming from one central location." A drone in follow-mode is, by design, parked directly over the vehicle it serves. It puts the brightest emitter the unit owns on top of a vehicle that may be carrying its leaders.

On power: in a well-planned network, "users can normally operate on low power, thereby decreasing the range, and making it more difficult for the enemy to detect and intercept transmissions." The same manual calls minimizing transmissions "the most effective preventive EP technique." A relay built for reach pulls against both.

Doctrine is not a veto. Commanders weigh these costs all the time. But the manual treats every elevated emitter as something to plan around, and the coverage of this test treated one as a jamming solution.

Two missions, two signatures

So separate what the tethered drone is doing, because the answer changes:

• Surveillance only, video on the cable. Low radio signature. The jamming claim is fair. The drone is still a physical object hovering over the vehicle, visible to eyes, cameras and radar, and it marks where the vehicle is. That is a different signature, and the cable doesn't hide it.
• Communications relay. High radio signature, by design. The drone's own link is protected. The relayed network is not, and its geometry now favors the enemy's intercept and jamming as much as the unit's own radios.

The Army's release describes both missions in the same set of iterations. The headlines only told the story of the first one.

What I could not confirm

I read the Army's article through a reprint. The piece, by Maddy Gonzalez, is on army.mil, but the site returned "access denied" and rate-limit errors to every attempt I made. I read the full text as republished by Soldier Systems Daily on 5 September 2026, which labels it a guest post, and every Army quote above is from that text. Army Recognition says the Army released it on 2 September.

The Army did not publish details of the jamming. The release doesn't say what was jammed, how hard, with what equipment, or what the relay radios were. I don't know whether the relayed network itself was ever jammed in the test. My point is about the geometry of any relay, not about a measured result.

I don't know how follow-mode tracks the vehicle. If it relies on GPS, that is another jammable input; if it keys off the vehicle or the tether, it isn't. The release doesn't say, so I don't claim either.

The "invisible" headline. I saw that headline, from the Belarusian outlet Charter'97, in search results. The page blocked automated access, so I didn't read the article and I rely on it for nothing beyond the words of its headline.

Doctrine edition. I read the 2016 edition of ATP 6-02.53 from an archived full text. The Army has since issued a revision. I have not read it, and its wording may differ.

Tether heights of 50 and 100 meters are illustrative, not the altitudes used in this test, which the Army describes only as "operationally relevant." The range figures are my own arithmetic from the handbook formula, over smooth earth.

The signal

A tether puts a drone's own control and video on a wire, and a jammer can't touch a wire. That part of the story is real. But the reason to lift a radio relay is to give it line of sight over the terrain, and line of sight is symmetric. The relay that lets your squad hear you from farther away lets the enemy hear you from farther away too, and lets a jammer reach you from farther away. When a report says a system "bypassed jamming," ask which link it means. Here the honest answer is: the drone's link, not the network the unit sent up with it.