TECHNOLOGY AREAS: Sensors, Electronics, Battlespace

ACQUISITION PROGRAM: Potential interest across all PEOs/PMAs

OBJECTIVE: Develop computational electromagnetic tools capable of characterizing the electromagnetic fields within Naval aircraft and the associated currents on avionic systems and their interconnecting cables in the operational electromagnetic environment. A key component of this tool is its ability to quantify the results in a stochastic sense in order to facilitate weapon system performance risk assessments.

DESCRIPTION: Naval aircraft come replete with interconnected electronic systems (e.g., communication, radar, and navigation systems). As the operating frequencies broaden and systems become more complex, their proper functioning is increasingly threatened by electromagnetic interference (EMI) from high-power external sources encountered in their operating environments [1-5] as well as internal sources. Because experimental testing of these systems’ electromagnetic compatibility (EMC) in their operational environments comes late in the acquisition process, simulation tools are needed to gauge their system level immunity to EMI [6] as early as possible in the program in order to minimize acquisition cost and timeline. For such simulation tools to be useful, they have to be capable of accounting for the complexities encountered with this problem. This includes computing the fields within Naval aircraft cockpits, cabins and equipment bays as well as currents on objects such as avionic systems and the cables that interconnect them. Computations must be done over a broad frequency range representative of the operational electromagnetic environments and a nearly infinite number of source geometries fields on and within these complex structures. Computations should consider the presence of (imperfectly shielded) coaxial cables as they present additional coupling paths for noise to propagate to sensitive circuitry [7-9].

In reality, the complexity of both the physical structures and the variability of the electromagnetic sources are the source of significant uncertainty. First, the source may be a variety of shipboard radar or communication systems illuminating the aircraft either on the flight deck or as it operates in close proximity to the ship. The aircraft may be in nearly countless number of locations and orientations relative to the source antenna. Second the physical structure of the cockpit and cabin are not constant. The presence of cargo as well as the aircrew can significantly alter the field within the aircraft. New computational technologies that permit the characterization of EMC/EMI phenomena in complex systems while accounting for their stochastic nature and uncertainties in their composition and input-output characteristics are needed.

PHASE I: Develop a detailed description of the scope of the electromagnetic vulnerability problem and determine the feasibility of computational electromagnetic tools employed to stochastically characterize the fields within cockpits, cabins and equipment bays of Naval aircraft. Assess the required fidelity aircraft geometry models in order to adequately characterize the fields and currents in a statistical sense. Initially, emphasis should be limited to source frequencies below 2 GHz but ultimately addressing problems through 17 GHz. Proposed methods should be justified by both theoretical and experimental analysis.

PHASE II: Develop, demonstrate and refine a prototype computational electromagnetic and stochastic inference tool capable of assessing Naval aircraft electromagnetic vulnerability. The tools are to focus on system level analysis and should be robust in the face of geometry model fidelity variability. Usability is a key performance parameter. The performance of these tools is to be assessed through both experimental and theoretical methods.

PHASE III: Develop a commercial application suitable for use in evaluating a wide variety of commercial and military systems.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: The technology developed under this topic has direct utility to a wide variety of commercial and military electronic EMC and EMI problems.

REFERENCES:
1. L. O. Hoeft, J. S. Hofstra, and R. Karaskiewicz, "Electromagnetic coupling through a row of aircraft windows for frequencies less than 100 MHz," presented at IEEE Int. Symp. EMC, 1993.

2. S. Guttowski, S. Weber, E. Hoene, W. John, and H. Reichl, "EMC issues in cars with electric drives," presented at IEEE Int. Symp. EMC, 2003.

3. E. S. Siah, J. L. Volakis, D. Pavlidis, and V. V. Liepa, "Electromagnetic analysis of plane wave illumination effects onto passive and active circuit topologies," IEEE Antennas Wireless Propagat. Lett., vol. 2, pp. 230-233, 2003.

4. S. Frei, R. G. Jobava, and D. Topchishvili, "Complex approaches for the calculation of EMC problems of large systems," presented at IEEE Int. Symp. EMC, 2004.

5. R. Neumayer, A. Stelzer, F. Haslinger, J. Held, F. Schinco, and R. Weigel, "Continuous simulation of system-level automotive EMC problems," presented at IEEE Int. Symp. EMC, 2003.

6. D. J. Riley, N. W. Riley, W. T. Clark, H. D. Aguila, and R. Kipp, "Electromagnetic coupling and interference predictions using the frequency-domain physical optics method and the time-domain finite-element method," presented at EEE Antennas Propagat S. Int. Symp., 2004.

7. F. Broydé and E. Clavelier, "Comparison of coupling mechanisms on multiconductor cables," IEEE Trans. Electromagn. Compat., vol. 35, pp. 409-416, 1993.

8. S. H. Helmers, H.-F. Harms, and K.-H. Gonschorek, "Analyzing electromagnetic pulse coupling by combining TLT, MoM, and GTD/UTP," IEEE Trans. Electromagn. Compat., vol. 41, pp. 431-435, 1999.

9. M. Feliziani and M. D.'Amore, "EMP coupling to multiconductor shielded cables," presented at IEEE Int. Symp. EMC, Japan, 1989.

KEYWORDS: Electromagnetic Interference; Electromagnetic Vulnerability; Statistical Electromagnetics; Electromagnetic Cavity; Radio Frequency Interference

TPOC: (301)342-2637
2nd TPOC: (631)673-8176