N221-015 TITLE: Electromagnetic Interactions Between Cables, Antennas, and Their Environments

OUSD (R&E) MODERNIZATION PRIORITY: Networked C3

TECHNOLOGY AREA(S): Electronics

OBJECTIVE: Develop a multifidelity simulation tool for analyzing electromagnetic interactions between cables, antennas, and their environments for Navy aircraft.

DESCRIPTION: Modern Navy aircraft are replete with cable harnesses that carry sensitive information and provide power to avionics, weapons, sensors, control surfaces, and landing gear. The internal arrangement and layout of cable bundles in aircraft is a critical part of the design of new and existing platforms. Rules of thumb for cable harness separation, shielding, and layout exist, but they often result in over-engineering the solution and are not always effective.

A need exists for a multifidelity cable harness tool that can be used during all phases of an aircraft�s life cycle to assess potential for self-interference, as well as disruption due to external sources such as EMP, HIRF, and lightning. NAVAIR analysts often need to provide rapid feedback regarding a design trade study or changes to a piece of avionics and its associated cables on an existing aircraft. As aircraft designs mature and more information about the structure of the platform, avionics, and cable harnesses becomes available, analysts want to work in the same tool leveraging the investment made in the previous analyses, all the way through to the simulation of the full aircraft for certification purposes.

The design process needs to consider cross-talk between cables within a harness or between cables in different harnesses. It must also include coupling to and from antennas located on the aircraft. There must be consideration for the electromagnetic compatibility of systems connected to the power bus, which becomes complicated as the number of systems on the same bus increases. Finally, a cable harness design should account for the impact of coupling from the external electromagnetic environment, including Electromagnetic Pulse (EMP), High Intensity Radiated Fields (HIRF) and lightning. All these interactions must be considered for cable harnesses in aircraft to understand the impact on the devices attached to the cables.

Multifidelity analysis tools exist that predict electromagnetic interference (EMI) between RF systems where the dominant coupling path is from a transmitting antenna to a receiving antenna. Such tools are extremely powerful for NAVAIR analysts because the same software tool can be used for quick, as well as rigorous analyses, and the models developed for a platform can be maintained throughout the lifecycle of that platform. However, a similar multifidelity solution for the cable harness analysis problem does not exist in a single software package. There are existing spreadsheet-based approaches for analyzing power buses. There are existing high-fidelity, full-wave solvers for analyzing the various modes of aircraft cable harness coupling. However, there are several limitations with existing approaches and tools. Spreadsheet-based solutions do not scale well with problem size, they are prone to errors, and make configuration control a challenge. Hybrid solvers, that include full-wave simulations of structures with transmission line modeling of cable harnesses, work well when all the necessary details are available to the analyst and there is enough time to build up the complex models of the platform with all the details of the various cable harnesses. However, this level of detail is usually not available until the design of the aircraft is almost complete. Medium-fidelity cable harness simulation tools based on modified transmission line theory are available. However, there is not a common platform to allow the medium-fidelity simulations to evolve as the design changes, and eventually incorporate the aircraft structure in a hybrid simulation. The compatibility problem must be set up for each environment individually, and they have, thus far, not been automated to consider multiple self-interference and external environments automatically.

PHASE I: Demonstrate solutions for low-, medium-, and high-fidelity approaches to the cable harness analysis problem considering both self-interference and external interference scenarios, such as those addressed in MIL-STD-461 and 464. Review approaches with NAVAIR technical staff to ensure that they fit the current and future workflow for NAVAIR programs. Develop a detailed software architecture plan for Phase II implementation that includes a user-friendly graphical user interface (GUI) and configuration control that allows for sharing of projects between groups working on different problems for the same platform (e.g., cross talk analysis, power bus analysis, and external field analyses). The Phase I effort will include prototype plans to be developed under Phase II.

PHASE II: Develop and demonstrate a robust, multifidelity software solution that allows NAVAIR analysts to consider very simple problems when there is limited information, all the way through full aircraft models with all the geometric, material, and cable harness details. Provide interfaces for reading common CAD formats. Demonstrate the accuracy, robustness, and speed of the tool. Develop a Phase III commercialization plan.

PHASE III DUAL USE APPLICATIONS: Complete development, and perform final testing and validation of a commercial grade application.

The tool is suitable for electromagnetic compatibility evaluation of any civilian or military electronic system, including within the commercial aviation and automobile industries.

REFERENCES:

1. German, F., Annamalai, K., Young, M., & Miller, M. C. (2010, July). Simulation and data management for cosite interference prediction. In 2010 IEEE International Symposium on Electromagnetic Compatibility (pp. 869-874). IEEE. https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=5711394.
2. Baum, C. E., Liu, T. K., & Tesche, F. M. (1978, November). On the analysis of general multiconductor transmission-line networks. Interaction Note, 350(6), 467-547. http://ece-research.unm.edu/summa/notes/In/0350.pdf.
3. Plumer, J. A. (1980). Protection of aircraft avionics from lightning indirect effects. In AGARD Atmospheric Elec.-Aircraft Interaction 26 p (SEE N80-31743 22-33. https://apps.dtic.mil/sti/pdfs/ADA087976.pdf#page=131.

KEYWORDS: Cable harness; cross talk; lightning; Electromagnetic Pulse; EMP; electronic vulnerability; electromagnetic interference