Field Coupling into the A380 Aircraft

1
Field Coupling into the A380 Aircraft
Dietmar Leugner, H.-D. Brüns leugner_at_tu-harburg.de
bruens_at_tu-harburg.de

• Introduction
• The field equivalence principle
• Special consideration for slots
• Demonstration by means of a small example
• Numerical model of the A380 aircraft with back
  doors
• Fully discretized model, EFIE problem
• Coupling-in results based on the application of
  equivalent currents of magnetic type
• Conclusion

2
Introduction

• Fully discretized MoM model
• 10219 unkowns
• Typical element dimensions from2 cm² to 2500 cm²

3
Introduction

• Loop antenna, HF range
• Numerically critical becauseof very low
  radiationresistance
• Stable solution only withinserted wire grid
• Validation power budget

4
Typcal results for the HF range (A380)
Radiation diagram at 30 MHz
Loop antenna input impedance

5
Huygens principle in electromagnetics

6
Transition slot / conducting part(problem of end
charges)

Possible solution
overlap
and inclusion of into the system matrix as
impressed current (to be done)
7
Illuminated sphere at 300 MHz

Field vectors in log. scale
Geometry
8
Coupled-in E field

9
Discretization of back door (1)

Surface currents at 30 MHz
Door 0.9m x 1.9m Slot width 1 cm
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Discretization of back door (2)

Details of slot discretization
11
Failure of classical EFIE (1MHz, 0)
Cross section of empty aircraft

Closed Model
Model with door
12
E field at 1 MHz generated by magnetic currents
(phase 0)
Cross section of empty aircraft

Vectors are plotted in log. scale
13
E field caused by magnetic slot currents
30 MHz
1 MHz

• Maximum magnitude of E in cross section of empty
  aircraft
• Aircraft structure completely neglected

14
Conclusion

• Small slots in large conducting bodies cannot be
  treated sufficiently by a MoM-EFIE approach
• Equivalent currents in slots and apertures acting
  as excitation sources provide an alternative
• Special treatment at the intersecting line of
  Huygens surfaces and MoM surfaces is necessary
• Application of purely magnetic slot currents give
  a first order solution
• The method works only if completely decoupled
  spaces are considered