Reactive RF Jamming Systems
FPGA-based · 20-8000 MHz · Reaction time from 18 µs
Defender-series jammers neutralize drone threats and disrupt modern telecommunications using FPGA-based reactive jamming. Operators define frequency ranges, power allocation, and jamming mode per mission — deployed to the jammer via software, no hardware changes.
What we build
B4 Limits develops the Defender line of FPGA-based reactive jamming systems for counter-UAS, correctional-facility, and telecommunications applications. Every system is designed and manufactured in Poland.
We build jamming systems where field evidence supports reliable performance — and only those. A jamming system is worth deploying only if its effectiveness can be demonstrated under real conditions, which is why the Defender line is shaped by laboratory research and field testing in equal measure.
Capabilities
Reactive Jamming
Semi-reactive detects threats and jams the entire configured range within 18 μs — medium power-to-range ratio. Reactive responds in 36 μs, jamming only the detected signal — maximum power-to-range ratio.
Power concentration and range
FPGA-based signal generation enables precise power allocation per threat frequency, delivering effective jamming at up to 3 km omnidirectional or up to 10 km with directional antennas against C1-class drones. Power is directed at the threat frequency rather than spread across empty spectrum.
Software-Defined Operation
Jamming behavior is defined by operator-created profiles uploaded via Leo control software. Each frequency range is independently configured — power, algorithm, and jamming mode. New threat: create a new profile, deploy in the field. No firmware updates, no hardware changes.
Operator safety
Fiber-optic separation keeps operators at a safe distance from the jammer during active operations. Defender systems are designed for remote deployment, minimizing personnel exposure to RF emissions.
Integration via REST and SAPIENT
Defender integrates into existing C-UAS architectures via REST API or NATO SAPIENT protocol. This positions the Defender as the defeat/engage layer within a complete detect-track-classify-engage kill chain, working alongside third-party radar, EO/IR, and RF detection systems.
Up to 8 hours continuous operation
Custom-engineered batteries optimized for the Defender power profile deliver up to 8 hours of continuous jamming at full output. Battery management extends operational runtime and equipment lifecycle.
Our Jamming Solution
Traditional jammers broadcast continuously across all frequencies, wasting power on empty spectrum. Defender's FPGA-based architecture enables three distinct operational modes — letting operators choose between maximum coverage (Active), balanced efficiency (Semi-Reactive), and precision targeting (Reactive) based on the threat environment.
Active
Semi - Reactive
Reactive
Applications
Deployment roles across counter-UAS, communications denial, and force protection
Defender systems are configured per project for the role they serve. Because frequency ranges, power allocation, and jamming mode are defined in software, one platform covers multiple roles without hardware changes.
In counter-UAS roles, Defender engages FPV and frequency-hopping drone control and video links, responding to each hop rather than broadcasting continuously across the band. For communications and cellular denial, it provides targeted denial of GSM, LTE, and 5G links within a defined area, from single-band targeting to wideband coverage. In convoy protection, broadband reactive coverage defeats radio-controlled triggers from a man-portable or vehicle-mounted platform. For fixed-site and critical-infrastructure protection, modular units deploy distributed for wide-area coverage or co-located to concentrate power on a defended approach.
Field-proven
Deployed, tested, and validated in real operational environments.
Defender Product Lineup
Every Defender jammer is built on the same FPGA-based reactive architecture — detecting threat transmissions and generating targeted jamming within 18 μs. Each unit is configured to the operational requirement and field-tested against live drone targets before delivery.
The product line spans two platform series. The Modular series scales from a single portable module to a multi-module array — combining units to reach the power, bandwidth, and coverage area of fixed-installation systems while remaining field-reconfigurable between missions. The Manpack series provides a self-contained man-portable jammer for dismounted operations, facility protection, and rapid deployment scenarios. Both series share the same reactive jamming modes, software ecosystem, and integration capabilities, and can operate together in a synchronized network.
Defender Modular Series
Scalable jamming platform — combine modules to match any mission scale
FPGA-based reactive jamming system that scales from a single man-portable module to a multi-module array operating as one coordinated jammer. Add modules to increase power, frequency coverage, and simultaneous bandwidth. Deploy modules co-located for concentrated jamming power or distribute them across terrain for wide-area coverage — all synchronized and managed as a single system through Leo control software.
Each module can optionally operate as a standalone jammer with full reactive capability. When combined, modules synchronize as a single system — scaling power and bandwidth with each module added while remaining field-deployable and reconfigurable between missions. Platform specifications are per module — total system power, bandwidth, and coverage multiply with the number of connected modules.
Single module capabilities:
Applications:
Defender Manpack Series
Man-portable configurable jamming system — 32 kg, IP66
Compact FPGA-based reactive jamming platform in a ~32 kg man-portable chassis. Configured per project for telecom denial, counter-UAS defeat or any combination — from narrowband precision targeting to wideband multi-threat coverage. Reactive mode concentrates all available power on detected threats, delivering effective range typically reserved for vehicle-mounted systems.
Applications:
Leo
Jammer control and monitoring softwareLeo provides centralized command and control for all networked Defender jammers. Role-based access separates configuration authority (profile creation and configuration) from field operation (one-touch activation of pre-set jamming profiles). Optimized for ruggedized tablet deployment with minimal processing requirements. Supports encrypted jamming profile distribution to prevent unauthorized configuration changes.
Lemur
Operator training and qualification platformLemur is a browser-based training platform that fully emulates Leo in a safe, RF-free environment. Operators progress through automated, structured exercises covering system startup, profile configuration, jamming activation and more. Supports self-paced individual training with built-in automatic assessment.
Company
B4 Limits was founded in 2019 by engineers with RF jamming expertise dating back to 2015. The team's first deployments served incarceration facilities, delivering proven cellular jamming systems that remain in active operation. In 2021, development began on the Defender counter-UAS platform — a 3-year program that produced a new generation of FPGA-based reactive jammers. Today, B4 Limits is a registered NATO supplier (NCAGE 99YVH, D-U-N-S 850906664) designing and manufacturing all hardware, firmware, and software in-house at our facility in Białystok, Poland.
EU-Funded R&D
The Defender reactive jamming platform was developed with co-financing from the European Regional Development Fund under the Smart Growth Operational Programme (POIR). The project advanced FPGA-based signal processing and reactive jamming algorithms from research through to field-validated production systems.
European Union
Republic of Poland