Why does signal integrity determine the effectiveness of defence systems?

Even a relatively minor electromagnetic disturbance can reduce radar range, disrupt communications, reset a computer, or distort transmitted information. During Evertiq Expo Kraków 2026, Dominik Kowalczyk of DACPOL addressed these challenges in his presentation, “The Impact of EMC Disturbances and the Importance of Signal Integrity for Defence Systems,” explaining why electromagnetic compatibility and signal quality are among the cornerstones of modern military technology.

From the analogue world to the digital domain

Dominik Kowalczyk began by highlighting the distinction between the analogue and digital worlds. Temperature, pressure, sound, light, voltage, and current are all analogue quantities. They change continuously over time. Digital electronics, by contrast, process information using a limited set of discrete values. For analogue signals to be useful in digital systems, they must be sampled, quantised, and represented in a discrete form.

The speaker compared this process to dividing a continuous image into individual frames. The more accurately a signal is represented, the more faithfully it can be reproduced in digital form. At the same time, however, the demands placed on the data-processing system increase.

“What we are looking for is a situation in which an analogue signal converted into a digital one remains an accurate representation of the original, stable and free from interference, distortion, and other undesirable effects,” Kowalczyk explained.

The challenge becomes increasingly significant as device performance continues to improve. Modern electronic systems are becoming smaller, more densely integrated, and capable of performing ever-greater numbers of operations within extremely short timeframes. Voltage transitions occur at very high speeds, meaning that phenomena which could once be neglected at lower frequencies can now affect the operation of an entire system.

Kowalczyk pointed out that individual signal components may be amplified to different degrees and may also experience timing shifts. As a result, particularly at high frequencies, even minor parameter deviations can distort a signal sufficiently for the receiving device to interpret information differently from what was originally transmitted.

The signal must arrive intact

Signal integrity describes the quality of a signal as it travels from the transmitter to the receiver.

“The goal is for the signal leaving the transmitter buffer to reach the receiver buffer in as close to its original form as possible,” Kowalczyk explained.

Between the transmitter and the receiver lies the transmission channel. As the DACPOL representative pointed out, this may consist of a PCB trace, a connector, a wire, or a cable. Each of these elements can degrade the quality of the transmitted information. In high-speed systems, both signal frequency and rise time become critical factors. Rapid transitions between low and high states cause PCB traces to behave as transmission lines. Their geometry, materials, routing, and termination determine whether a signal reaches its destination correctly, is reflected, attenuated, or distorted.

One of the primary challenges highlighted by Kowalczyk is impedance mismatch. When a signal encounters a sudden change in the electrical characteristics of a transmission path, part of its energy may be reflected. Factors such as conductor width and thickness, transitions between PCB layers, laminate properties, and even minor variations in material parameters can influence signal behaviour. The speaker also drew attention to crosstalk – the unwanted interaction between adjacent signal traces.

“We have two traces running next to each other. If they are placed too close together or are not designed properly, one can affect the other,” Kowalczyk illustrated.

A signal travelling along one trace generates a changing electromagnetic field, which can induce voltage in a neighbouring circuit. As a result, the receiver not only receives the intended information but also an unwanted signal generated by the adjacent trace.

Kowalczyk further explained that signal degradation can also be caused by noise, frequency-dependent losses, and the skin effect. In the latter case, high-frequency current tends to concentrate near the surface of a conductor rather than flowing evenly throughout its cross-section. Addressing one problem may create another. Increasing the width of a trace, for example, can reduce certain losses but simultaneously alters its impedance. According to the speaker, designing high-speed electronics requires continuous trade-offs between competing performance parameters.

Electromagnetic compatibility in practice

While signal integrity focuses primarily on preserving information quality within the transmission path, electromagnetic compatibility (EMC) addresses the broader relationship between a device and its environment.

As Dominik Kowalczyk explained, well-designed equipment should meet at least two fundamental requirements. It must be resistant to external disturbances while also avoiding the emission of interference that could disrupt the operation of other devices. In some cases, a third aspect is considered as well: a design should not interfere with its own operation.

“EMC focuses on the interaction between devices and their impact on one another. Signal integrity is concerned with the signal itself,” the DACPOL representative summarised.

Interference can propagate either through radiation, via electromagnetic fields, or through conduction, for example along power and signal lines. Kowalczyk noted that common sources include switching power supplies, converters, motors, control systems, circuit switching, contact bounce, and electrostatic discharge (ESD).

Particularly significant sources of interference are rapid voltage transitions. Kowalczyk explained that fast switching events generate electromagnetic energy across a broad frequency spectrum. In practice, this means that even a single component can influence numerous other subsystems operating nearby.

An electronic chain of operations

The importance of EMC in the defence sector stems from the way modern armed forces operate. As Kowalczyk explained, sensors monitor the environment, recognition systems classify objects, communication networks transmit data, command centres make decisions, and fire-control systems execute the mission.

Together, these elements form an extensive chain of dependencies, often referred to as the kill chain. It encompasses the successive stages that lead from target detection and identification, through decision-making and engagement, to the assessment of operational outcomes.

“Disrupting this chain at any point can cause the entire system to fail, prevent it from operating as intended, or reduce the functionality of a platform or device at a local level,” Kowalczyk noted.

As demonstrated in the examples he presented, a loss of signal integrity in a radio communication system can result in a loss of connectivity. In radar systems, interference can reduce range, accuracy, and target-detection capability. In a fire-control system, errors may affect targeting precision, while in an onboard computer they can lead to resets, system freezes, or other unpredictable behaviour. Although such issues can occur in civilian equipment, on the battlefield their consequences directly affect mission success and personnel safety.

Drones – a network of dependencies

One of the examples highlighted by the speaker involved unmanned aerial vehicles (UAVs). In its simplest form, the operator sends commands to the drone, and the drone transmits data back. However, as Dominik Kowalczyk pointed out, the real-world picture is far more complex. Radio signals do not travel solely along a dedicated communication link between the operator and the UAV; they propagate through space and can therefore be detected, jammed, or used to locate the transmitter.

The situation becomes even more complex when several or even dozens of drones operate simultaneously. Each platform must communicate with the operator or with other assets while avoiding excessive interference with neighbouring systems. Kowalczyk noted that a swarm may consist of multiple types of platforms, including reconnaissance drones, loitering munitions, strike UAVs, and larger strategic systems. These platforms operate at different altitudes, at varying speeds, and under changing environmental conditions. Coordinating their activities therefore presents a significant electromagnetic compatibility challenge.

A similar situation arises in systems where an aircraft or a ground vehicle operates alongside a group of unmanned platforms. According to the speaker, the continued development of such systems further increases the importance of reliable communications and effective control of electromagnetic emissions.

Interference as a strategic tool

Dominik Kowalczyk reminded the audience that electromagnetic disturbances are not always merely an unwanted side effect. In the defence sector, they can be deliberately employed to deceive radar systems, disrupt communications, and reduce an adversary’s operational capabilities. The concept itself is far from new. The speaker referred to the metallised strips dropped by aircraft during World War II, which created radar reflections resembling genuine targets. Today’s countermeasures are significantly more sophisticated, but they rely on the same underlying physical principles.

Intentional interference is also used during testing and validation. As the DACPOL representative explained, engineers introduce pulses, voltages, and electromagnetic fields with carefully defined characteristics to evaluate how a device behaves under extreme conditions. This makes it possible to assess the robustness of a design before it reaches a certification laboratory or the end user.

Particularly valuable are pre-compliance tests conducted during the prototyping phase. Near-field probes can be used to identify areas of a PCB that generate excessive electromagnetic emissions.

“We can move such a probe across the PCB and identify the areas that are ‘radiating’ the most, to put it simply,” Kowalczyk said.

The speaker emphasised that these measurements do not replace full laboratory testing. They do, however, allow engineers to detect design issues at an early stage, when corrective actions are considerably easier and less costly to implement before production begins.

From design to a resilient platform

Dominik Kowalczyk stressed that electromagnetic resilience is established long before a device enters service. It begins at the design stage, where key engineering decisions largely determine a system’s ability to withstand electromagnetic disturbances throughout its operational life.

Once a design has been finalised, additional protective measures can be employed. Among the solutions mentioned by the DACPOL representative were ferrites, conductive gaskets, shielded enclosures, filters, and honeycomb ventilation structures designed to protect airflow openings while maintaining electromagnetic shielding.

To illustrate the challenge, Kowalczyk referred to an armoured vehicle, where numerous electronic systems operate within a confined space. Each system emits electromagnetic energy, each may be susceptible to external interference, and all must function simultaneously without disrupting one another.

Electromagnetic compatibility should not be treated as an afterthought introduced at the end of a project. Instead, it must be considered from the earliest stages of system design.

As network-centric warfare systems, drone swarms, collaborative platforms, and high-energy weapons continue to evolve, the importance of EMC will only increase. Faster electronics provide greater computing and communication capabilities, but they also become more susceptible to phenomena that could previously be ignored. In modern defence systems, effectiveness depends not only on the destructive power of the weapon itself, but also on whether information transmitted by a sensor, radar, computer, or command post reaches its destination on time, intact, and exactly where it is needed.

The next edition of Evertiq Expo Kraków will take place on 9 June 2027. Before then, the electronics industry will gather in Warsaw on 22 October 2026, where Dominik Kowalczyk will once again take the stage. Registration for the event is now open.