Dr Thomas Withington Last updated: January 17th, 2024
Drone Frequency Jammers
Unmanned or uninhabited Aerial Vehicles (UAVs) are tricky targets to detect and engage. The small physical size of some of these aircraft can make UAV detection difficult both visually and via radar. Materials used in UAV construction, like plastic and carbon fiber, can conspire to give the aircraft a small radar signature. A small signature can make these aircraft difficult to detect by radar.
The challenge of detecting and tracking a UAV by radar, or by visual means, makes these targets hard to engage kinetically. The inherent difficulties of kinetic engagement has encouraged other approaches to be taken in the fight against hostile UAVs.
Unmanned aircraft depend on electromagnetic energy in the form of radio waves, known formally as Radio Frequency (RF) energy, to fly. A radio link will connect the aircraft to its human pilot in a similar way to how a remote control connects the viewer to their television. A drone may use a radio link to share video or still imagery, or other data and information it is collecting, with the pilot or with the UAV’s sensor operator. This data is usually carried across an RF datalink.
UAVs may depend on Global Navigation Satellite System (GNSS) constellations to fly. The aircraft will receive Position, Navigation and Timing (PNT) signals from a GNSS constellation which help the aircraft to ascertain its position and thus compute its flight path. Like the RF link connecting the pilot to the aircraft and facilitating the datalink GNSS PNT signals use RF energy.
The dependence a UAV has on radio signals brings potential vulnerabilities which can be exploited to neutralize these aircraft should they present a threat. RF energy can be used to detect, identify and track a UAV. Radio frequency energy can also be employed against these aircraft to jam the radio links they depend on.
Globally, several frequency bands are either reserved, or made available, for UAV use. At the international level, these frequencies are allocated by the International Telecommunications Union (ITU). The ITU is the United Nations body tasked with globally regulating use of the radio spectrum.
13 frequencies and frequency bands are earmarked by the ITU for UAV Command and Control (C2). C2 is the catch-all term covering the piloting of the drone and the exploitation of its sensors. These C2 frequencies are parceled up into a segment of the radio spectrum stretching from 27 megahertz/MHz to 5.8 gigahertz/GHz.
Drone C2 Frequencies
In practice, 90 percent of drone operators use frequencies of 2.4GHz and 5.8GHz for drone C2. UAVs have a host of GNSS constellations they can use for aircraft PNT signals including the United States’ Global Positioning System, the European Union’s Galileo, the People’s Republic of China’s Beidou and Russia’s GLONASS. All these constellations provide PNT signals on a waveband of circa 1.1GHz to 1.6GHz.
Disruptions to C2 & GNSS Signals
Many drones employ failsafe mechanisms to stop them flying if they encounter disruptions to their C2 or GNSS signals. This provision is designed to prevent the aircraft from continuing to fly in an unpiloted fashion in a similar way to how the Dead Man’s Handle works on a train. The driver must continue to activate the Dead Man’s Handle while they are driving the train. If the control is not activated the train’s brakes are automatically applied to prevent the train continuing without human supervision. In the event of the drone losing the C2 or GNSS signal it will either automatically land in situ or return to the flight’s point of origin. Logic dictates that if the C2 or GNSS RF links can be interrupted then the drone will either land or return to base.
ANCILE Counter UAS RF Shield by Allen Vanguard
Aiming an RF jamming signal in the direction of a hostile UAV could seriously impinge the aircraft’s ability to fly. The jamming signal will need to be more powerful than the C2 or GNSS signal the UAV relies on to prevent the aircraft receiving these latter two transmissions. The UAV will not be able to ‘hear’ the GNSS or C2 signal above the more powerful jamming. Unable to continue receiving these signals the UAV’s fail-safe mechanisms will activate and the aircraft will either land or return to its point of origin.
It may be possible for the jamming signal to be used as a means of ‘hacking’ into the UAV’s control system to let someone take control of the drone. With the aircraft under their control, the hacker could either force it to land or fly it to a place where they can take possession of it. Similarly, the UAV could be jammed with a fake signal mimicking the PNT transmissions the drone is receiving. This counterfeit signal could be used to keep the UAV away from certain places or to fly it to another location.
Drone RF jammers come in many shapes and sizes: Individual rifle-style designs are available which are physically pointed in the direction of the drone to ensure the jamming signal is aimed at the correct target. Larger vehicle-mounted counter-UAV systems often pair a jammer with another effector like a kinetic system. Vehicle or deployable systems may include radar, optronic and RF-based drone detection systems providing a self-contained counter-UAV ensemble. RF drone jammers are found in a wide array of locations protecting key places like sports stadiums and big events such as summit meetings, to deployment at the tactical edge on the battlefield.