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Russian Patent Signals Effort to Adapt Tank Active Protection Systems to FPV-Type Drone Threats.
Russia has patented a new active protection system method designed to engage attack drones as well as missiles and projectiles. The filing underscores how FPV drone warfare is reshaping armored vehicle survivability and future tank design.
On 24 December 2025, documentation published by the Federal Institute of Industrial Property (FIPS) indicated that the Kolomna-based Design Bureau of Mechanical Engineering (KBM) has received a patent for an active protection system (APS) method capable of engaging not only missiles and projectiles but also attack drones. This development comes after several years in which Russian tanks, including the T-90M “Proryv”, have suffered heavy losses to first-person-view (FPV) drones and precision-guided munitions in Ukraine. The patent, registered as No. 2853544 with a validity start date of 23 May 2025, formalises a technical approach that seeks to address one of the most critical vulnerabilities of modern armour: very small, slow, and low-cost drones operating at short range. Against the backdrop of Russia’s ongoing efforts to integrate the Arena-M APS on T-72B3M and T-90M tanks, the filing signals an attempt to move away from improvised anti-drone cages toward a more integrated and algorithmic counter-drone protection layer.
The image is for illustrative purposes only and shows T-90 tanks fitted with the Arena-M active protection system, reflecting Russia’s broader effort to adapt armored defenses to the growing threat posed by FPV attack drones (Picture Source: Uralvagonzavod)
The patent describes, first, a refined method for the classic role of an APS: intercepting fast incoming missiles and projectiles. In the baseline mode, a Doppler radar scans the space around the armored vehicle and detects an incoming round when it crosses a first fixed “waiting distance.” At that instant, the system measures the target’s coordinates, Doppler-derived radial velocity, and the exact time of the measurement. Using these data, the processor repeatedly commands new “waiting distances” closer to the vehicle, each reduced by at least the product of the measured Doppler velocity and the time required for the radar to generate a new range gate. This effectively walks the radar’s focus inward along the expected trajectory until the target enters the APS “kill zone”, defined as the region in which the interceptor’s fragmentation pattern can reliably disable the incoming threat. In parallel, the processor runs a prediction algorithm that uses successive coordinate measurements, associated Doppler velocities, and time intervals to estimate the point and moment at which the threat will cross into that zone. On that basis, the system selects one protective round from its magazine and commands its launch and detonation so that the directed fragment field intersects the calculated entry point.
The core innovation of the patent is the extension of this logic to deal with small multirotor drones, which do not fit the assumptions of traditional APS radars designed for supersonic or high-subsonic munitions. In the proposed method, the radar periodically switches from the long-range waiting distance used for missiles to a second, shorter fixed distance dedicated to drone surveillance. At this closer range, the radar is not looking primarily for the drone’s body, whose radar cross-section can be very small, but for the characteristic micro-Doppler modulation produced by its spinning propellers. The blades create a distinctive “radar noise” signature that can be made to pass through filters otherwise tuned for high-speed threats, allowing the system to see the drone as if it were a fast object for a brief moment. Once detected, the drone’s coordinates are measured repeatedly over time. Initially, the processor assumes a maximum technical speed for the drone and sets a new waiting distance reduced by at least the product of that speed and the radar’s re-timing interval.
As more coordinate samples are collected, the algorithm replaces this conservative estimate with the drone’s current speed, calculated by dividing the distance between successive coordinate points by the time between measurements. From then on, each new waiting distance is reduced by at least the product of this measured speed and the radar’s update time, again stepping the focus inward until the drone reaches the APS kill zone. The drone’s trajectory is predicted using only these coordinate-based velocities and time intervals, explicitly excluding Doppler parameters to avoid errors caused by the low and variable radial speeds typical of hovering or maneuvering multicopters. Once the estimated impact point and time are known, the system again selects and fires an appropriate protective munition to intercept the drone.
Hardware-wise, the patent specifies an APS architecture closely aligned with existing Russian concepts. It includes a Doppler radar linked to a signal path with a Doppler filter that passes only echoes from objects moving faster than approximately 20 m/s, a threshold chosen to suppress ground clutter and very slow-moving objects in the classical anti-missile mode. A processor controls range-gate switching and trajectory prediction, while a separate selection unit issues commands to individual protective munitions arranged around the vehicle. The new elements introduced for drone engagement are, first, a timer that periodically toggles the radar between the long-range missile waiting distance and the short-range drone distance; and second, a dedicated computing block that divides the measured trajectory segment lengths by the corresponding time intervals to derive coordinate-based speeds for drones.
These additions allow a single radar and processor to manage two distinct threat classes, fast projectiles and slow drones, without fundamentally changing the launcher hardware. In practice, the patent refers generically to an “active protection system of an armoured vehicle” and does not mention Arena-M by name. However, Russian media reporting explicitly links the patent to the Arena-M system and illustrates it using existing diagrams of Arena’s mode of operation, implying that KBM intends the method as an evolution of that family rather than an entirely new APS.
Open sources provide a baseline understanding of Arena-M’s current design and deployment status, which is necessary to interpret the patent’s significance. The Arena family, originally developed in the late Soviet period, uses a roof-mounted radar and a ring of near-field hard-kill munitions around the turret to intercept incoming anti-tank guided missiles (ATGMs), rockets, and high-explosive anti-tank (HEAT) rounds at short range by detonating a narrowly focused cloud of fragments into their path. Recent reports indicate that experimental batches of T-72B3M and T-90M tanks with Arena-M have been produced and delivered to the Russian Ground Forces, though their operational use at the front remains unclear and apparently limited. Russian and Western reports indicate that Arena-M, as currently implemented, primarily covers the frontal and lateral hemispheres and remains vulnerable to top-attack munitions and overhead FPV drones. In early 2024–2025, KBM’s chief designer Valery Kashin publicly acknowledged ongoing work to adapt Arena-M for protection against loitering and strike drones. The available evidence therefore supports the assessment that the patent describes a software- and radar-centric enhancement intended to be retrofittable to existing Arena-M installations, even though the legal text itself stays generic.
If implemented as described, the method could provide several tactical advantages relative to existing Russian APS capabilities. First, by exploiting the micro-Doppler signature of rotating propellers, the system attempts to solve the central problem Russian engineers have highlighted: making small, low-speed drones “visible” to radars designed for much faster targets. Periodic switching between long- and short-range modes allows the same sensor hardware to serve dual roles, reducing the need for separate counter-drone radars. Second, the coordinate-based tracking algorithm for drones is designed to remain robust even when Doppler data are unreliable or ambiguous, which is often the case when FPV drones fly at shallow angles, maneuver aggressively, or skim close to the ground. Third, by relying on the same hard-kill protective munitions as in missile interception, the system promises a common “last line” of defense against ATGMs, rocket-propelled grenades, artillery submunitions and, now, some classes of attack UAVs, potentially reducing logistic complexity. On paper, such an APS could create a hemispherical protective bubble of a few tens of meters around a tank, complicating the employment of single FPV drones or small quadcopters attempting to approach from the flanks at low altitude.
However, the available open-source record underscores that translating this concept into reliable battlefield performance will be technically challenging. Ukrainian and Western reporting has stressed that current Arena-M prototypes struggle to detect mini and micro UAVs built from low-visibility materials, particularly when they fly against complex ground clutter at very low altitude. The micro-Doppler approach described in the patent may mitigate this to some extent, but it also increases the risk of false alarms, since birds, wind-blown debris, and civilian quadcopters can produce comparable signatures. High false-alarm rates are a serious issue for hard-kill APS, because each engagement consumes limited ammunition and carries a non-negligible risk to nearby friendly troops in the fragmentation cone.
Furthermore, the patent does not by itself resolve geometric limitations. Arena-M installations documented so far provide little coverage directly above the turret, an angle frequently exploited by top-attack ATGMs and diving FPV drones. To improve survivability against these threats, Russian units have often resorted to heavy “anti-drone cages” or shed-like superstructures that physically shield the roof but, in turn, can interfere with APS line-of-sight and fragment dispersion. Integrating the patented method with such ad hoc protections without mutual degradation of performance will be a significant integration problem.
Beyond the technical domain, the patent has operational and strategic implications for Russia and for NATO. For Russia, the formalisation of this dual-mode APS reflects a recognition that the main killers of tanks in Ukraine are no longer primarily man-portable anti-tank weapons but artillery and drones, especially cheap FPV systems guided via commercial radio links. If KBM can successfully implement and field the patented method on a meaningful share of T-72B3M and T-90M fleets, Russian armor could gain a measure of resilience against single-drone attacks, forcing Ukraine and its partners to rely more heavily on saturating swarms, top-attack profiles, or alternative kill chains (for example, targeting logistics or command nodes).
At the same time, industrial and financial constraints, sanctions, and the complexity of fitting APS to large numbers of tanks make rapid, wide-scale deployment unlikely. For NATO, the filing confirms that Russian industry is moving beyond simple cages toward integrated counter-drone solutions, even if these are still experimental, and that future Russian armored formations may be better protected against the types of threats now dominating the Ukrainian battlefield.
From a broader geostrategic perspective, the patent exemplifies the emerging global competition between offensive drone technologies and vehicle-mounted protective systems. Israel’s Trophy APS, widely integrated on U.S. and Israeli platforms, has demonstrated effectiveness against ATGMs but has also had to evolve in the face of loitering munitions and complex multi-axis attacks. Russian efforts to upgrade Arena-M along the lines described in patent 2853544 indicate a parallel attempt to keep pace with this evolution under more constrained conditions. Even if the Russian solution remains imperfect, its eventual appearance in operational theaters would influence the cost-exchange ratio between drones and armored vehicles, potentially driving further innovation on both sides: for example, stealthier FPV airframes, autonomous swarm behaviors designed to saturate APS magazines, or combined arms tactics that pair drones with electronic warfare to blind or confuse the radar. For the United States and its allies, this highlights the need to think of APS and counter-drone systems as integrated, software-driven defensive ecosystems, rather than as discrete add-on kits, and to anticipate adversary adaptations in doctrine, not just in hardware.
The new Russian patent should be viewed as an indicator of intent and direction rather than as evidence of a fully solved engineering problem. The method it describes, dual-mode Doppler radar surveillance, micro-Doppler detection of rotors, and trajectory prediction based on coordinate-derived speeds, offers a coherent conceptual path to extending existing hard-kill APS against at least some classes of attack drones, likely within the framework of Arena-M, even though that system is not named in the patent itself. At the same time, open-source reporting suggests that Russian engineers have not yet overcome the fundamental sensing and algorithmic challenges posed by very small, low-signature UAVs in cluttered environments, and that Arena-M remains limited in deployment and unproven in high-intensity combat.
The key message is that Russia is institutionalising and protecting intellectual property around counter-drone extensions to its APS portfolio, which will likely translate into iterative hardware and software upgrades over the coming years. This development warrants close monitoring of fielded vehicles, test ranges, and combat reports, but it does not yet require a fundamental reassessment of the vulnerability of Russian armor to Western-supplied drones, artillery, and anti-tank systems.
Written by Teoman S. Nicanci – Defense Analyst, Army Recognition Group
Teoman S. Nicanci holds degrees in Political Science, Comparative and International Politics, and International Relations and Diplomacy from leading Belgian universities, with research focused on Russian strategic behavior, defense technology, and modern warfare. He is a defense analyst at Army Recognition, specializing in the global defense industry, military armament, and emerging defense technologies.