Better Shielding and Fewer Test Cycles with Early EMC Simulation

Electronics engineers already invest significant effort in minimizing interference at the source through clean layout, filters, grounding concepts, and signal integrity. However, in A&D platforms, this alone is not sufficient. As soon as lightning, high-intensity radiated fields (HIRF), active jammers, or densely packed avionics racks come into play, the shielding of enclosures, cables, and connections against electromagnetic fields determines whether systems function reliably in operation.

What Electromagnetic Shielding Must Deliver in Time-Critical A&D Environments

• immunity = what your system must safely withstand
• emission = what your system is allowed to emit

Standards define limits, but real A&D environments are often more demanding: onboard radars and Link-16 terminals generate near-field strengths well above typical test values. Jammers and electronic warfare (EW) systems can create high field strengths in specific frequency bands. In highly condensed avionics racks, multiple transmitters, clocks, and RF sources combine into an extremely challenging electromagnetic environment.

Electromagnetic shielding is one of the most important tools to address both sides. It protects against external interference while also limiting what your system emits. Designing this correctly from the outset not only reduces EMC risks but saves what matters most: time in qualification and certification, as fewer non-compliances occur during testing.

What Defines Good Electromagnetic Shielding in A&D?

Electromagnetic shielding reduces or blocks fields using conductive or magnetic barriers. It works mainly through two mechanisms:

• reflection of fields at conductive surfaces
• absorption, where energy is dissipated within the material

Shielding performance is described by shielding effectiveness (SE) in decibels:

Examples:

• 20 dB → 10× reduction
• 40 dB → 100× reduction
• 60 dB → 1,000× reduction

In A&D applications, designs typically consider the worst case. Adding “a bit more shielding” afterward is rarely an option. If shielding is not considered early in system design, additional prototypes, redesigns, and certification loops are likely – delaying readiness.

Where Electromagnetic Shielding Consumes Time and Effort

Many EMC issues do not arise in idealized models but in unavoidable details – seams, openings, cables, and connectors. And this is exactly where test campaigns tend to drag on.

Enclosures, Seams, Openings

Production introduces tolerances: surfaces are not perfectly flat, and gaps, doors, access panels, and ventilation slots often open the Faraday cage precisely where field strengths are highest. As a rule of thumb, openings should be significantly smaller than λ / 20 of the relevant wavelength.

Even small slots can act like antennas, making enclosure design and sealing critical. If such effects are only discovered during EMC testing, additional mechanical iterations are almost inevitable.

Cables and Connectors

Unshielded or poorly terminated cables behave like antennas: they radiate internal noise and pick up external fields. Ground loops and common-mode currents further amplify interference. Poor shielding or routing also introduces crosstalk in cable bundles.

Any later change to the wiring harness – different shielding, alternative routing, additional ferrites – costs time, money, and often extra test days.

PCB Interfaces

Where connectors or cables meet the PCB, multiple domains converge: high frequencies, high power, and sensitive signals. Missing local shielding or unclear return paths turn these areas into hotspots.

EMC Simulation in A&D: Targeted Shielding Instead of “Adding Metal Just in Case”

One approach might be to add more metal and specialized shielding in critical areas. However, especially in A&D, where every gram and millimeter matters, this quickly increases costs and extends development time – without guaranteeing that the actual EMC issues are solved.

This is where electromagnetic simulation focused on EMC challenges comes into play: it shows early in the development process where and how protection measures work and which variants are most likely to pass testing on the first attempt.  With tools such as Ansys HFSS and Ansys EMC Plus, you can answer questions such as:

• How do field strengths inside an enclosure change when adjusting slots, ventilation, or sealing concepts?
• Which material, wall thickness, or coating combination delivers the required shielding effectiveness without excessive weight?
• How do different cable configurations affect immunity and emissions?
• Where are the actual coupling paths between power electronics, avionics, radar, and communication?

Analysis of the electric field distribution (electric field) inside and outside the enclosure, as well as measurement of the field strength at a point (field probe) at a distance from the device and the cable. | © CADFEM Germany GmbH

This turns electromagnetic shielding from a “trial-and-error metal” approach into a measurable design parameter: field distributions, current paths, and shielding effectiveness can be evaluated already in the concept phase. This reduces surprises in testing – and therefore the number of redesign and retest cycles that delay time to readiness.

Best Practices: Embedding Shielding with EMC Simulation Early in A&D System Design

1) Consider Shielding from the Start

Shielding does not belong at the end of design but in the architecture phase: enclosure concepts, cable routing, interfaces, and PCB design should be considered together. This avoids late-stage gaps and saves iterations in integration and qualification.

2) Plan Mechanics and Electronics Together

Shielding is closely linked to the mechanical design of a product. Mechanical and EMC teams should early on define where space is needed for gaskets, additional fasteners, continuous reference planes, and shielded zones.

3) Focus on Hotspots

Electromagnetic simulation helps quickly identify critical areas:

• seams, ventilation openings, access panels
• cable feedthroughs and connectors
• transitions between shielded and unshielded zones
• areas with high field strengths due to PCBs or power electronics

This ensures detailed engineering effort is applied where it has the greatest impact on EMC testing and schedules.

4) Simulate Iteratively Instead of Monolithically

Start with simplified models such as closed enclosures or idealized shields and gradually add real details like slots, gaskets, and realistic cable bundles. This keeps computation time and complexity manageable while providing early, reliable insights for your EMC strategy.

5) Always Consider Shielding, Filtering, Grounding, and Layout Together

Successful EMC concepts in A&D rarely rely on a single measure. Shielding, filters, grounding, and layout form a combined system – and EMC simulation is the tool to design this system coherently instead of optimizing measures in isolation.

Electromagnetic Simulation as the Key to Faster EMC Testing and Operational Readiness

In aerospace and defense, shielding is a core element for meeting radiated emission limits, fulfilling high immunity requirements under real operating conditions, and passing EMC tests on the first attempt whenever possible.

This is where EMC simulation shows its strength: it reveals how enclosures, cables, and sealing concepts actually perform and enables you to optimize shielding measures early and effectively. This turns intuition into reliable design decisions – and EMC risks into manageable variables on the path to an operational A&D platform.