Abstract-The increased use of carbon-fiber composites in Unmanned Aerial Vehicles is a challenge for their EMC assessment by numerical solvers. For accurate and reliable simulations, numerical procedures should be tested not only for individual components, but also within the framework of complete systems. With this aim, this paper presents a benchmark test case based on experimental measurements coming from direct-current injection tests in the SIVA unmanned air vehicle, reproduced by a numerical Finite-Difference-Time-Domain solver that employs a new subgridding scheme to treat lossy composite thin panels. Validation was undertaken by applying the Feature Selective Validation method, which quantifies the agreement between experimental and numerical data.

As part of the technology research engaged in the EU Clean Sky 1 project, we present in this paper an electrical structure network (ESN) designed to prevent the impact on an electronic equipment of unwanted voltage drops appearing when nonmetal composite materials are used for grounding. An iterative process has been followed to reach an optimal tradeoff solution meeting all the aircraft requirements: structural, safety, low weight, electrical, etc. Guidelines on the design of a low-impedance metal ESN, to minimize the inductive behavior of the power distribution network, are outlined in this paper. To this end, we employ the UGRFDTD simulation tool, combining finite-difference time domain to analyze the general EM problem, and a multiconductor transmission-line network to handle internal coupling between cables running along coinciding routes. The capability of this tool to create time-domain snapshots of surface currents is shown to provide a useful way to optimize the ESN, thanks to the insight gained on the physics of the problem. Index Terms-Carbon-fiber-reinforced plastic (CFRP), electrical structure network, electromagnetic compatibility (EMC), finite-difference time domain (FDTD), green regional aircraft (GRA). I. INTRODUCTION T HE design of an aircraft (A/C) must comply with the aerodynamic, structural, safety, fuel efficiency, cost, and electromagnetic (EM) requirements, among many others, this requiring the parallel work of several departments. Clean Sky 1 is one of the largest European R&D projects focused on the design of the A/C of the future: low-CO 2 and highly cost-efficient air-transport system. Its objective is to speed up the technological breakthrough developments and to shorten the time-to-market for new solutions that introduce green technology into aviation. Within the framework of Clean Sky 1, this paper deals with the design of low-weight configurations Manuscript

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A novel conformal technique for the FDTD method, here referred to as Conformal Relaxed Dey-Mittra method, is proposed and assessed in this letter. This technique helps avoid local time-step restrictions caused by irregular cells, thereby improving the global stability criterion of the original Dey-Mittra method. The approach retains a second-order spatial convergence. A numerical experiment based on the NASA almond has been chosen to show the improvement in accuracy and computational performance of the proposed method.

This paper describes the analysis of the experimental test results obtained during the low level swept coupling (LLSC) and low level direct drive (LLDD) tests on FALCON 7X horizontal tail plane provided by EADS-CASA. These techniques are evaluated during the aircraft high intensity radiated field (HIRF) certification process and in the scope of European Community's FP7 HIRF SE project. The analysis of low level test results shall be performed to estimate the influence of the test setup with particular regard to the in-flight coupling configuration. For this reason, finite difference time domain (FDTD) 3D computations have been used to determine the relationship between free field external radiation and skin current in different illumination angles and polarizations. Finally, after validation by comparison of the measured and computed skin current, measured bundle current are related to measured skin currents, to provide the transfer function link to the external field.Keywords-electromagnetic compatibility (EMC); aircraft; low level swept current (LLSC); low level direct drive (LLDD); high intensity radiated field (HIRF); finite difference time domain (FDTD); validation; skin currents; coaxial return.