Opening Insights
Electromagnetic interference (EMI) and electromagnetic compatibility (EMC) are often underestimated risks in small satellite missions—until they become mission-critical failures. From corrupted telemetry to disabled sensors and failed payloads, EMI-related issues can wreak havoc on satellite performance and reliability. As smallsats increasingly integrate complex electronics into tightly packed enclosures, verifying EMC through proper testing is now a necessity.
Electromagnetic environments are becoming more challenging as well— high-power electronics, and onboard radios all contribute to potential cross-coupling and emissions. EMI/EMC qualification ensures that a spacecraft will function as intended, both internally and in the shared RF landscape of space.
Understanding EMI and EMC
EMI refers to any unwanted electromagnetic energy that disrupts system performance of a spacecraft. This can be caused by various internal sources (e.g., switching power supplies, clocks, RF transmitters).
EMC is the ability of a system to operate reliably without emitting excessive interference or being unduly affected by interference from other systems. A fully EMC-qualified spacecraft can perform its mission with various systems coexisting onboard .
In small satellite platforms, where space is limited and multiple subsystems are tightly located, managing interference requires rigorous design practices and comprehensive testing protocols. As Mallette and Adams (2011) note, many EMI failures are rooted in design—not test—underscoring the importance of early mitigation.
Why EMI/EMC Testing Is Critical for Smallsats
While large space programs often follow well-established EMI/EMC protocols, smallsat missions have historically skipped or abbreviated these steps due to budget or time constraints. That approach is no longer tenable. Modern CubeSats and smallsats frequently operate sensitive payloads, complex avionics, and high-frequency radios—all of which are vulnerable to EMI.
Common failure modes include:
With launch providers and spectrum regulators tightening standards, many rideshare missions now require formal EMI/EMC testing as part of flight readiness reviews.
Key Testing Objectives and Approaches
The core goals of EMI/EMC testing are:
Testing typically includes both conducted (through power and signal lines) and radiated (through free space) EMI paths. These tests are executed in shielded environments, such as anechoic or semi-anechoic chambers, to eliminate external interference and enable controlled stimulation.
Borsi et al. (2019) demonstrated a practical approach to EMC testing for smallsat power distribution units. Their campaign included Conducted Emissions testing at low frequencies and Radiated Susceptibility testing up to 1 GHz. By combining simulation with measurement, they were able to validate both compliance and safety margins in their subsystem design.
Common EMI Sources in Smallsats
Smallsats are uniquely vulnerable to EMI due to their high component density and limited separation between noisy and sensitive circuits. Some common culprits include:
Additionally, the metal enclosure of a smallsat may act as an unintended antenna or reflector—amplifying interference effects unless properly grounded and shielded.
Simulation and Pre-Test Design Practices
While testing is essential, EMC success begins with design. Chahat et al. (2025) describe how the NASA SWOT mission’s EMI/EMC qualification campaign used high-fidelity electromagnetic simulations to pre-validate spacecraft performance. These models predicted field coupling between subsystems, signal reflections, and emissions from key components—enabling targeted mitigation before hardware was even fabricated.
Best practices for EMI-aware design include:
Smallsat teams increasingly leverage simulation tools like CST, HFSS, and SPICE to identify and solve EMI problems early—reducing costly redesigns during environmental testing.
Test Facilities and Setup Considerations
EMI/EMC testing requires specialized facilities, including:
Smallsats may be tested as full flight models or via subsystem-level campaigns. Test configurations must replicate flight-like operational states—including powered payloads, active communication links, and nominal data flows. Test duration, bandwidth coverage, and dwell time are often defined by ECSS, MIL-STD-461, or NASA GEVS standards.
Subsystem Compatibility and Interference Scenarios
In compact spacecraft, internal EMI between subsystems can be just as hazardous as external exposure. A GPS module may be jammed by onboard UHF transmitters. A sun sensor might show data dropouts due to switching harmonics in a nearby regulator. Power bus noise can ripple through analog payloads, degrading measurement quality.
EMC testing helps reveal these interactions by powering the entire spacecraft during emissions and susceptibility runs. Engineers can monitor subsystem telemetry in real time, correlating disturbances to RF signatures and identifying root causes.
Some teams also run compatibility matrices—turning on and off various combinations of subsystems while measuring emissions and system stability—to ensure robustness under worst-case operating scenarios.
Certification, Reporting, and Documentation
Formal EMI/EMC qualification requires detailed test planning, documentation, and result reporting. Test campaigns should be traceable to mission requirements and linked to system-level risk assessments. Test reports typically include:
This documentation becomes part of the spacecraft’s compliance package for regulatory approval and launch integration. In rideshare contexts, non-compliance can result in flight rejection or mandated requalification.
Conclusion
As small satellites evolve into mission-critical platforms, EMI/EMC testing is no longer optional—it’s essential. With compact layouts, mixed-signal systems, and limited shielding, smallsats face real challenges in managing internal and external interference. But with proactive design, robust simulation, and comprehensive testing, teams can achieve full electromagnetic compatibility while maintaining performance and reliability.
From initial schematic to final chamber test, EMI awareness must be woven into the spacecraft development process. The result: safer launches, clearer communications, and more resilient missions.
Explore More
Discover EMI test services and compliant avionics systems in the Testing Services and Flight Hardware categories of the SmallSat Catalog. The SmallSat Catalog is a curated resource for small satellite builders, offering tools and technologies to manage interference and ensure electromagnetic compatibility.
Recommended Reading:
Chahat, N. et al. (2025). EMI-EMC Qualification of the NASA SWOT Mission Using High Fidelity Modeling.
