Efficient Modeling Of The Electromagnetic Environment In A Cabin Illuminated By External Fields

The flight safety of a modern aircraft is threated by the increasingly complex external electromagnetic environment. The external electromagnetic environment is mainly composed of transient electromagnetic field, electrostatic discharge, high-intensity radiated fields(HIRF). These external fields can penetrate into the cabin through windows, cabin door edge and other channels, and then enter the equipment by coupling with cable. This complex electromagnetic coupling behavior is an important part of electromagnetic environment effects(E3) of civil aircraft study.Focusing on the efficient modeling of the electromagnetic environment in a cabin illuminated by external fields is studied as follows:1. The iterative physical optics(IPO) is used to calculate the electromagnetic environment in the open cabin. For the high computational complexity, low calculation efficiency problems of the classical IPO method, the equivalent dipole moment(EDM), the fast dipole method(FDM) and the multilevel fast dipole method(MLFDM) are combined with IPO to simplify and accelerate the IPO integral computation, and realize fast calculation of the electromagnetic environment in the electrically large cabin. By using the EDM, numerical integration in the iterative formula of the IPO can be expressed directly into an analytical formula. a closed-form solution of the IPO integral is derived. Thereafter, to accelerate the calculation of the IPO integral, the interaction of each two bases in two nonadjacent groups is transformed into the form of aggregation-translation-disaggregation by using the FDM. Finally, the computational efficiency of the IPO is further improved by combining the MLFDM with IPO method.2. The modeling of electromagnetic environment coupling on the twisted-wire pair and the complex cable bundles is analyzed by using Baum-Liu-Tesche(BLT) equations. Introducing the concept of ideal junction, the overhead twisted-wire pair is transformed to multi-conductor transmission line network. When the twisted-wire pair and shield cable are placed in the complex cable bundles, the equivalent cable bundle method(ECBM) and the BLT equations are combined to solve the electromagnetic environment problem of the complex cable bundles. The simulation results are indicated that the method can reduce the computational complexity and improve the efficiency of modeling. Thereafter, combined the fast IPO methods with the BLT equations, a modeling approach for dealing with the field-to-wire coupling problem of the twisted-wire pair and complex cable bundles inside an open-ended cavity is proposed.3. To analyze the static electromagnetic environment distribution of an equivalent scaled cabin model, which is place with the mode-stirrer, the model data generated by automatic finite element mesh generation software PATRAN can be utilized fully by combining with the grid data interface program written in Visual fortran 6.6. This leads to the establishment of the cabin’s mathematical model. Shadowing technique is adopted before using the fast IPO methods to calculate the electromagnetic environment in the cabin. The numerical examples are given to verify the validity of the algorithm.