2. “A Computational Framework for Aircraft Design and Certification to
Minimize the Risk of Electromagnetic Interference”
The research leading to these results has received funding from the European Community’s Seventh Framework Programme [FP7/2007-2013] under
grant agreement no 205294. This support is gratefully acknowledged by the HIRF SE Partners. We would like to thank the members of the HIRF SE
Advisory Board, the EC Reviewer Team and the Project Officer Mr. Daniel Chiron, for their advice during the project.
Eng. Luigi Pisu, Electromagnetism Department, Alenia Aermacchi

3. GENERAL INFORMATION
• Project full title: HIRF SE (High Intensity Radiated Field Synthetic Environment)
• Coordinator: Alenia Aermacchi
• Starting Date: 1/12/2008
• Ending Date: 31/05/2013
• Budget Total/Funding: 26,5 M€ / 17,8M€
• Type of project: Collaborative Project - Large Scale Integrating Project (CP-IP)
• HIRF SE Consortium comprised 44
partners from 11 EU member states
• HIRF SE Consortium was composed by
Airframe manufacturers, Large
Industries, SMEs, Universities and
Research Center
• Most qualified research groups in Europe
& worldwide
• Alenia Aermacchi was the Coordinator
The materials in this presentation (hereafter the Materials) are the property of Alenia Aermacchi spa (Alenia). Any use of the Materials without
previous approval by Alenia in writing is forbidden. The information in the Materials is provided solely for the purpose of illustration. Alenia does
not guarantee the validity of the Materials and shall not be liable for unauthorized use of the Materials. © Alenia Aermacchi – All rights reserved

4. INTRODUCTION
WHY WAS THIS PROJECT NECESSARY?
• Before air vehicles (A/C & R/C) can fly, must be assured, in the frequency range 10KHz-40GHz, that:
1. Equipment and subsystems are not affected by mutual EM interactions (EMC)
2. Subsystems/systems can correctly operate when subjected to external EM disturbance (EMI)
• Certification Authorities (EASA and FAA) require demonstration against possible critical effects
A. Novel air vehicle concepts (FBW) have led to a
high increase of electronically-controlled
functions the failure of which can have
catastrophic effects
B. Proliferation of high-power electromagnetic
emitters
 Increase of testing time to ensure compatibility
with existing and future regulations
© Alenia Aermacchi

5. INTRODUCTION
• Experimental verifications are carried out at the later stages of the product development
• Very high rework costs associated to EM defect detection during the Qualification Phase
EM weaknesses
during the
design
EMC/HIRF
Testing
• Testing is not always fully representative of In-Fly
conditions due to ground influence and to the
difficulty to reproduce the real Far-Field condition
on laboratory
 Last revision of ED107 Certification Guidelines
already suggested the introduction of correction
factors (obtained by analysis) to take into account
the ground influence
WHY WAS THIS PROJECT NECESSARY?

6. THE CONTEXT
PROJECT OBJECTIVES
• HIRF SE is a Computational Framework that permits, by simulation:
• to predict air vehicles EM performances during the design phase, minimizing the
rework activities
• to support certification testing verifying air vehicles robustness with respect to EM
disturbances, improving the current safety level of air vehicles
• Maintain time & costs associated to testing “under control”
• HIRF SE can be applied during design and certification phases with the following
objectives:
• To mitigate air vehicle EM vulnerabilities
• Optimize qualification EMC/HIRF testing at equipment level and certification
EMC/HIRF testing at air vehicle level
• Concentrate EMC/HIRF testing where air vehicles need (susceptibility analysis)
• Allow a more comprehensive assessment of the electromagnetic coupling

7. THE FRAMEWORK
HOW DOES HIRF SE OPERATE?
• Given the external operative scenario, the Framework computes, in the FR 10kHz-40GHz:
• Air vehicle external EM environment
• Air vehicle Internal environment surrounding each equipment under analysis, in terms of
induced cable currents and electromagnetic fields
• And it calculates the related Transfer Functions:
1. Current flowing into equipment connectors Vs External EM threat [dBμA/V/m]
2. EM field surrounding equipment Vs External EM threat
0
10
20
30
40
50
60
0,1 1 10 100
Frequency [GHz]
ElectricField[V/m]
Potential susceptibilities to be mitigated
• TFs on the whole A/C to be compared with
equipment qualification levels
• Green Curve: Equipment Qualification
Mask in terms of Tolerable V/m
• Violet Curve: HIRF SE – Transfer Function
of EM field surrounding the same
equipment installed on the A/C

8. Pre-Processing
[FDTD] [MoM] [PWB]
3D Solvers [FDTD or MoM] + MTLN
Materials - Cables/Connectors
10KHz - 3 GHz
HIRF SE
Framework -
HDF Format
A/C
meshed
model
EM
Parameters
Post-Processing
2D and 3D display of results
PWB Solvers
Materials / Structures
Up to 40 GHz
CAD Cable
Architecture CAD Structure
FRAMEWORK BLOCK DIAGRAM

9. EM incident field
characteristics
(polarization,
frequency range)
Materials
Internal 3D geometry
(dense or not dense)
External 3D geometry
(size and shape)
Apertures
Furniture, seats
Wiring system
Bonding /Grouding
Slot /Seams
Equipment
(Input impedance and
absorption)
Observables:
• Internal/External EM
environment
• Induced currents
• Transfer function
MODELING COMPLEXITY

10. • The numerical codes constituting HIRF SE have been assessed and validated by comparison with
measurement results (about 70 test cases)
• Massive and extensive campaigns of :
 Testing
 Simulation
 Analysis of results (FSV, IELF)
• Two main levels of validation process:
 On “simple”/geometrical controlled test cases
 On 9 real Air vehicles
0.001
0.01
0.1
1
0.1 1 10 100
H/Iijected
Freq (MHz)
H / I_injected
HY1_MARCH PT1_FUS_HY
FRAMEWORK VALIDATION PROCESS
• The convergence between measurement and simulation results happens only if the three
conditions are verified:
1. The electromagnetic phenomena are correctly represented by the implemented
computational algorithms
2. The test set-up is well known and correctly modelled
3. The numerical model of the object under test is enough representative of the HW ones

11.  Framework Validation process followed the principle of “Increasing complexity of the test objects and test
cases”
VALIDATION PROCESS ON “SIMPLE” TEST CASES
 To improve reliability of results:
 The same test case carried out by different test
houses
 Same observables measured with different
measurement methodologies
 Simulations performed using different
computational codes (FD, TD, TLM, PWB)
Testing/Modeling Complexity
17 cm

12. FRAMEWORK VALIDATION ON A REAL AIR VEHICLE
 Demonstrate the possibility to use the HIRF SE framework as support for design & certification of
systems installed on-board against HIRF effects by showing the comparison between measurement
and simulations on a typical Use-Case.
 An Use Case: “Robustness evaluation, against EM threats of Piaggio P180 Avanti II Attitude and
Heading Reference System”
 Highlight the strict correlation between testing and simulation processes and consequentially their
complementariness
 The P180 A/C was subjected to a certification-
like testing campaign against HIRF on the
Alenia Aermacchi Anechoic Chamber and
Open Area Test Site in March 2012.
 The testing campaign consisted of the LLSC
task on two electronic equipment installed on
the A/C nosecone
 Measurement and evaluation of the coupled
current [1-400MHz] on the equipment
dedicated bundles due to an external
irradiative scenario.
by courteously of Piaggio Aero Space

13. LOW LEVEL SWEPT CURRENT: TESTING PROCESS
1. Free Space Test Site Calibration on 5 points
 3 V/m Target at the table center (O) in FR [1-30
MHz] (only in the OATS)
 10 V/m Target at the table center (O) in FR [30-400
MHz] (both inside and outside)
 E-Field on points [A,B,C,D] stored → “Iterative
tuning process” between Real (measured) and
Virtual (simulated) incident EM scenario
2. Aircraft illumination from 4 angles [45°, 135°, 225°, 315°] and 2 perpendicular polarizations,
and simultaneous measurement of the coupled current [dBμA], about 20 cm far from the Computer
connector
 Nosecone (containing equipment under test) positioned within the area around points [A,B,C,D]
3. TF [dBμA / (V/m)] obtained normalizing the current with respect to FS E-Fields on points [A,B,C,D]
 Measurements carried out twice (both in AC and in OATS) in the FR [30-400 MHz]
by courteously of Piaggio Aero Space

14. 3D – MODELING STRATEGIES & CAD MANAGEMENT
The original CATIA CAD was subdivided in different catpart /product files organized for aircraft zones
(Cockpit, frames, structures, LRU, cable bundles...)
CAD of Cable
Bundles
Nose (external part)
Frame
(internal part)
Equipment
by courteously of Piaggio Aero Space

15. • The CAD product files imported in the IDS-IT AEMMesher pre-processing
module
• Cleaning activity performed eliminating the large amount of small details
(screws, bolts, clamp connections, small holes, surface thickness….)
• Topological discontinuities removed with the help of cleaning tools
(integrated into the framework)
• All Bundles approximated as “tubes”, bonding points short-circuited,
connectors simplified
Structure CAD cleaned ready for EM Meshing & Simulation
3D – MODELING STRATEGIES & CAD CLEANING
by courteously of Piaggio Aero Space

16. • The external and internal structure was meshed taking into account aircraft materials
• The induced current on cables & internal/external surfaces obtained by the IDSMMMP
3D solver (FD Solver – MoM)
Mesh of External
structure
Mesh of Internal structure
Mesh of Cables and Equipment Internal distribution of Induced
current on the nosecone
3D – MODELING STRATEGIES & MESHING
by courteously of Piaggio Aero Space

17.  Complete Transfer Function Worst Case (among the 8 radiative scenarios, as required by
standard) [dBμA/V/m] & Envelope Difference [ Red Simulation – Green Measurements ]
Acceptable Results. The P/F procedure shows some minor
deviations around 20MHz and around 300MHz mainly due to the
difficulties faced in the Setup Modeling.
 Simulation hypothesis and the application of Pass- Fail
criteria lead to conservative condition
+6dB
-6dB
LLSC: MEASUREMENT VERSUS SIMULATION
Curves Envelopes
Envelops difference

18. SUMMARY
1. HIRF SE is a SW framework able to incorporate different computational codes dealing with
electromagnetic phenomena
2. The modules composing the framework have been validated through a massive campaign of
real testing on simple test objects and on real A/C and R/C
3. Main scope of HIRF SE is the computation of air vehicle structure EM attenuation and of the
“unwanted” currents flowing trough the wiring network
 General applications of HIRF SE Framework
 Evaluation of electromagnetic performances of an air vehicle during the design phase (Risk of
rework reduced)
 Tailoring equipment qualification test (design phase)
 Support of Air vehicle certification for Level A systems
 Applicants for certification must validate their EM models (by demonstrating convergence
between simulation and measurement results). Once validated the model, the rest of
certification campaign can be carried out by simulation
 Testing always to be used as benchmark to validate air vehicle EM models

19. Thank you for your
attention
The research leading to these results has received funding from the European Community’s Seventh Framework Programme [FP7/2007-2013] under
grant agreement no 205294. This support is gratefully acknowledged by the HIRF SE Partners. We would like to thank the members of the HIRF SE
Advisory Board, the EC Reviewer Team and the Project Officer Mr. Daniel Chiron, for their advice during the project.