There are many weapons and systems being used in the war in Ukraine that have been labeled as game changers by various commentators, such as the Javelin ATGM, the Bayraktar TB-2, or the HIMARS. However, none of these systems make as big a daily impact on the conflict on the ground as the small cheap commercial camera drone. As armies all over the world are going to have to develop and equip specific counters to them, lest they be vulnerable in future conflicts.
The most dangerous soldier on the battlefield is not the one carrying a specific type of weapon, but rather the humble radioman. Because he is able to call in attacks of all types from afar on an enemy position. And to do that job properly they need correct and up to date information on the enemy location and disposition. That is where these drones come in. Where originally you had to send a soldier to scout out the enemy, either on foot, or in a vehicle of some sort, you can now do the same thing with drones without putting the soldier at anywhere near as much risk from being killed by the enemy. And while military drones do exist that perform this task, they are often orders of magnitude more expensive and made in much smaller numbers (though they do come with features such as jamming resistance that commercial drones do not). Despite the vulnerabilities that commercial drones have, their extremely low cost and wide availability make them a continued valid asset to use. They can be replaced almost as quickly as they are lost in the current conflict. But this also means that future state and non-state actors will likely acquire and use them due to the low barrier to entry into this vital capability.
So, what are the challenges out there facing militaries all over the world in countering these types of small commercial drones that are so readily available?
Detection
To first counter a threat properly you must first detect it. There are multiple ways of detecting drones, each with their own advantages and disadvantages. Detection of these small commercial drones is particularly difficult, not only due to their small size, but also the fact they tend to fly relatively close to the ground, meaning that there are all kinds of ground clutter and other things hampering detection.
When it comes to detection methods, they are put into two camps, active and passive sensors. Active sensors emit something outwards, like a radio wave (radar), and look for a return of this signal. While passive sensors do not need to emit anything to work. Instead looking for what is already there like the light that bounces off of things (this is how a camera, as well as our eyes operate). Or the passive sensor may be looking for signals that a potential enemy is emitting themselves, such as their radio transmission. Active scanners generally allow for greater accuracy and control in sensing over passive sensors but come at the expense of giving away your presence to anyone who has passive sensors that can pick up the signals you are putting out with your active sensors.
Radar
Radar is the most common means of detecting objects in the air for a long time, and it is not at all surprising that it is also the industry standard currently for detecting drones.
Radar works by emitting radio waves from a transmitter, that will reflect off of an object and travel back to a receiver (usually paired with the transmitter) and through complex calculations of time and frequency of these returned radio waves to determine the distance and speed of an object relative to the radar system. This helps make radar very accurate and a valid system for targeting moving objects. Another advantage of radar is that radio waves have a much easier time moving through things such as cloud and fog, thus allowing for the detection of objects that would otherwise normally be hidden from sight.
One of the challenges with attempting to detect a drone with radar, is the small physical size of these drones. This gives a drone a small Radar Cross Section (RCS), which leads to greater difficulty in detection, especially at longer ranges.
The downside of radar though is that due to the need to emit radio waves to operate, it is capable for other systems to pick up its presence with only just a set of receivers. Giving away that someone is operating in that area, and even roughly where. Not good information to supply to an enemy.
Radio Frequency Detection
Radio frequency detection works by having a set of radio frequency receivers spaced out over an area, that can detect the radio waves the drone emits to transmit back to the control unit. Normally such a receiver can only know the direction the radio signal is coming from, but by having multiple receivers and spacing them out, then using trigonometry, and seeing what the time difference is between receiving the radio signal at each receiver, they can pinpoint the drone’s location. It may even be possible to detect the location of the drone control unit doing this.
The downside of Radio Frequency Detection is that if you want to know more than only the heading of the radio signal, you will need multiple receivers spaced out. That is why we generally see singular receiver systems who mainly act as a warning system, to alert users of the presence of a drone operating in the area.
Acoustic Detection
Acoustic detection works by having a set of microphones that will detect sounds and then seeing what the time difference between reception at each microphone is, calculate where the origin point of the sound is. In the case of drones the system would be listening for the distinctive sound that the propellors make. An interesting thing is that a database of sound signatures can be built up allowing such a system to recognize the specific type of drone and thus provide additional information.
Another interesting thing is that gunshot detectors already work like this and are an increasingly more common piece of equipment in law enforcement and the military. This means that companies making this type of equipment need only work on the software end of things to get these kinds of capabilities installed. However how far they can accurately detect remains to be seen. And much like with Radio Frequency Detection, to get an accurate position of the drone, the system would need to be built up out of multiple parts spread out over an area.
Electro-optical Detection
Electro-optical is a fancy way of saying using electronic cameras to detect something. These can be ordinary light spectrum cameras, thermal heat sensing infrared, or low light illumination (night vision in common parlance), often with high magnification capability so objects far away can be viewed in greater detail.
Here again the small size of the drone makes it difficult to spot. And the use of brushless electric motors mean that they have a small heat signature as well.
These types of systems are generally already part of existing detection systems and will generally be used for getting positive identification of the drone detected. That is the camera system will be used to view what is suspected to be an enemy drone to confirm that it indeed is. Since you do not want to be accidentally shooting a friendly drone or something else friendly or perhaps innocent.
The downside of these systems is that the necessity to have greater magnification capability limits these sensors from having a wide field of view (FOV), meaning that they can only see so much of the world at once, and since the sky is rather big, they make for a poor means of trying to spot for drones.
Infrared Search and Track (IRST)
Infrared Search and Track systems use thermal sensors to scan for and detect heat signatures. Here a sensor continuously rotates around 360 degrees so as to scan a wide tract of the sky and detect any heat signature. It then by comparing the scene of each rotation, which can be less than a second apart, it can detect new heat signatures. And over the course of multiple rotations track the potential target’s movements.
There are very few downsides to these types of systems, the major one being that outside of aircraft use, they are rather rare, and so there are few suppliers. But I personally suspect that we are likely to see that change the coming decade.
LIDAR
Laser Imaging Detection And Ranging, better known by its acronym LIDAR works similarly to how radar works, but instead uses a laser rather than a radio wave. The system emits out a laser, and a detector looks for how long it takes for part of the laser light to be reflected back and as a result know the distance to the object. This is also how laser rangefinders work, but unlike them, a LIDAR system will be emitting over a wide area to build up a picture. And by performing multiple sweeps it is able to detect differences and so detect new objects and track movement.
LIDAR is in common commercial use as a sensor for autonomous vehicles and robots, but despite decades of research papers talking about using LIDAR as an aircraft detection system, it has yet to ever be developed. As so while a promising system, I don’t see it actually being fielded anytime soon.
Suppression
Once a drone is detected one way of dealing with it is by suppressing its operations rather than just outright destroying it. Drones operate remotely by sending and receiving radio signals to and from the operator. Among these radio signals will be things like GPS location data, video feed, control inputs, and telemetry (information on the drone and its systems). All this data is transmitted over radio waves, and if you know what frequency these transmissions are taking place in, you can fill the air with a stronger radio signal on the same frequency, thus drowning out the data transmission and making the controller unable to operate the drone. This is called jamming. Most commercial drones are even programmed to immediately go down and land when they lose connection to their controller, and this is how you have seen most of the drone captures in Ukraine take place.
If you happen to know the drone protocol (how commands are made) it is even possible to read everything the drone is transmitting, and even insert your own commands to capture the drone (Journalists would generally call this hacking the drone). Due to using common commercial drones, this has in fact happened a fair bit in the fighting in Ukraine, though it is something that hardly ever gets reported on.
Not every drone operates under the same frequency and so jammers intended to counter not just a single type of drone need to be able to put out their signal on a wider band of frequencies to be effective against multiple types of drones. This however requires more power to do. And there are now some companies out there that make small drones like these commercial drones, specifically for military use. Part of making them suitable for the military is making them more resistant to jamming. One way of doing that is by having the capability to hop frequencies while in mid-operation. Where the drone looks for frequencies that are available for use and switches to that when they start getting jammed. So, if you want to counter drones with this kind of capability your jammer needs to be able to operate across a wide band of multiple frequencies at the same time, requiring yet more power.
One of the downsides of jamming in a warzone is that you are putting out a lot of radio energy into the air doing so, and this energy can be picked up by the enemy using sensors just like in radio frequency detection mentioned above. And since actively jamming puts out far more energy into the air to be detected compared to controlling a drone, such efforts are much more easily picked up, and at longer ranges, by an enemy that has the equipment to detect such efforts.
There now even exist man portable anti-drone jammers. They resemble futuristic guns out of some sci-fi movie with their big antennae. These systems due to their portable nature have lower power outputs and thus range. But they have proven effective at countering drones that do stray to within their range in recent conflicts like Syria and Ukraine.
Destruction
The most effective means of denying the enemy the use of their drone is of course through destroying it, but that is easier said than done. Since these drones are smaller than a person, often a long distance away, and can be moving at pretty significant speeds. And it can become even harder if the drone operator tries to keep the drone mostly hidden in cover like trees or buildings to only pop out to conduct his task. This all together makes it pretty much impossible to try and shoot down a drone with any weapon system that doesn’t have some form of fire control system to aid in an accurate engagement. This means that any man portable system outside of some missile systems is out of the question for this task.
One family of weapon systems that is already in widespread use that can engage and destroy drones, are the various surface to air missile systems. These can either be fire-and-forget systems that lock onto a drone’s heat signature to guide themselves in, or they can be guided in by the firer with the use of radar, laser or radio. These missile systems also come in sizes from small man portable launchers that a single person can operate (Called Man Portable Air-Defence System or MANPADS in the military), to missiles the size of a man, or even a small bus. All of these larger missiles needing a vehicle to carry and launch them, though the smaller man portable missiles can also be mounted onto vehicles.
However, while missile systems exist that can engage and destroy these types of drones, relying solely on them would be foolish. As these missiles can costs tens of thousands, if not hundreds of thousands or even over a million dollars. Meanwhile the drones cost maybe a few thousand at most. Not to mention the drones can be produced and acquired with relative ease, unlike advanced missiles. Meaning that sole reliance on missiles will eventually see an army run out of missiles before a determined opponent can run out of drones. For this reason, a cheaper more cost-effective weapon should be sought out for destroying drones.
Considering the difficulty of hitting these drones at distance, the best solution is to instead use a weapon system that fires rounds with a proximity fuzed high explosive round. These are rounds are outfitted with a small radio frequency sensor and transmitter which together operate like radar to detect how close the shell is to a passing object, and once within a certain distance it will detonate, sending out a cloud of shrapnel that will damage or destroy objects nearby. Because with such rounds you need not get a direct hit, only get within a certain distance, the chances of destroying a drone are greatly increased. However due to proximity fuzes being of a certain size, and the effectiveness of explosive rounds being related to the size of explosives, proximity fuzed rounds only appear in cannon rounds, generally those of 30mm and up.
Autocannons firing these types of rounds were extremely popular with the military in the years immediately following the end of WW2, but as jet aircraft got faster and able to engage targets effectively from greater altitudes, they slowly fell out of favour for missiles. But they started to make a slow resurgence as the threat from helicopters started to be perceived, and now so too with drones. With many of these autocannons and their ammunition being proven designs, their introduction into service is much less risky than designing a new system from scratch.
In contrast to the tried-and-true autocannons, the other system that is being developed specifically to counter drones are lasers. They hold a lot of promise for accurate engagements at range.
Lasers work by focusing a beam of light onto a single point, and by having a more powerful beam, that light will then heat up the surface of whatever it is illuminating, which in turn can get hot enough to damage or destroy components. Which on these small drones would be generally easy since their components are made to be light so as to fly efficiently, especially so for commercial drones. Also due to the laser beam traveling at the speed of light it makes engaging targets much easier, provided the system is accurate enough to place the beam on the target and keep it at the same point.
The downside of lasers though is that just like light, they are affected by everything in the atmosphere like water vapour, dust, clouds, etc. These all absorb or scatter the laser light, making it get weaker as it travels over a distance. On even a clear day an infrared laser loses half its strength over a distance of 4 km. Meaning that a 30 kilowatt beam is only 15 kilowatt at 4 kilometers distance. And this degradation over range is made worse with higher levels of humidity.
One challenge with laser weapon systems outside of just the massive power requirements, is that the laser systems generate a tremendous amount of heat, and that heat needs to be shed to keep the laser functioning. And these cooling systems take up space and have their own energy requirements too. Which is why we are seeing laser weapon system development focused mainly on ships, due to their larger size and power generating capacity being able to more easily accommodate the laser system.
Conclusion and Future
To conclude there are many ways of tackling the threat posed by small drones, each with their own advantages and disadvantages. So where should armies of the future be looking to focus their efforts?
Most of the efforts before the outbreak of the war in Ukraine were focused on proven technologies, mainly small radars for detection, and jammers to suppress and disable the drones. This is due to the assumption that the threat of these drones would come mainly from non-state actors such as insurgents or terrorists. So, there were very limited worries about enemies having the capability to detect the emissions from these systems in operation by using their own passive sensors, and then conducting an attack on their location.
The war in Ukraine however shows that state conflicts can still happen, and that armies will field these commercial drones in larger numbers, often paid for by soldiers out of their own pocket. This is not just due to the low cost and availability of these drones, but also the fact that the commercial drones are often superior to what the military itself fields. Because the commercial world can innovate and bring to market products far faster than the military bureaucracy can.
The focus for the immediate and near future should thus be on the development and fielding of passive sensors, so drones can be detected without potentially giving your position away to the enemy. While weapons and munitions that are cheap to use, but effective at taking out drones should be fielded. So that an enemy cannot just simply attrition out an effective but small stockpile of anti-drone munitions.
Since these drones rely on commercial image sensors, they do not work well in the night. By putting a greater emphasize on night fighting and minimizing your footprint during the daytime, an army will be able to reduce the effectiveness these drones can have. However, it is not a guarantee, since there are some drones out there with thermal cameras that can operate at night.
Another thing is that almost every single system mentioned in this article require a continuous power source in order to operate. The only exception being the man portable anti-drone jammer, and the man portable air defence system. Though they do both require batteries that may need replacing or recharging in the field, especially the man portable anti-drone jammer.
That means that in the future electrical power generation in the field is going to be of vital importance to securing an area and keeping soldiers safe. Especially those soldiers who are dismounted and cannot just simply rely on systems installed on vehicles. Or the cases where equipment installed on vehicles cannot operate effectively, like in a heavily built-up area, so a portable system needs to be installed on the roof of a tall building. Thus, it would also be prudent for militaries to put an effort into the production and fielding of portable generators.
I don't agree that a non-missile man portable system is out of the question, the XM25 looks like it would be ideal for the task.
https://en.wikipedia.org/wiki/XM25_CDTE
Maybe the best way to deal with enemy drones is through autonomous killer drones.
Cheap autonomous AI controlled drones should be able to scan for enemy drones and put a bullet in those that it finds.