Center for Electromagnetic Compatibility (EMC) Proposal #1128748 Proposal #1127923
This proposal seeks funding for the Center for Electromagnetic Compatibility located at the Missouri University of Science and Technology and the University of Houston site, respectively. Requests for Fundamental Research are authorized by an NSF approved solicitation, NSF 10-601. The solicitation invites I/UCRCs to submit proposals for support of industry-defined fundamental research.
This proposal will provide a novel insight into EMC coupling path physics, especially in complex geometries such as systems and printed circuit-boards. The project will provide solid theoretical and numerical basis for coupling path direction, which can open an entirely new solution strategy for EMC problems, thus transforming the practice of electromagnetic problem solving in EMC and provide the industrial consortium members with a practical and useful diagnostic and mitigation methodology.
The availability of coupling path detection methods can drastically improve the understanding of complex EMC problems, enabling more functionality to be integrated into products as diverse as high-speed electronics, automobiles, or military hardware. The proposed project will help assure the relevancy of the research to industry and ensure that results will be integrated into the development of real products that make their way to the consumer. The center will gain the unique capability to visualize coupling paths; this will allow an increase in the scope of the center by addressing additional audiences.
This research focuses on developing methods to identify and visualize electromagnetic coupling paths. The basis of the approach is to utilize an analogy between electromagnetic energy flow and fluid flow. This allows one to apply the theories and algorithms of fluid dynamics to electromagnetics and thereby to visualize the electromagnetic energy flow. This, in turn, can be utilized to identify the electromagnetic coupling path. The basic idea of the method is introduced in figure 1 which shows a parcel path and the similarities between fluid dynamics and electromagnetics used. The basic principle is solving the continuity equation which relates the energy density to the flow of the pointing vector. Since the energy flow and fluid flow obey the same equation, the theories and methodologies of fluid dynamics can be applied to electromagnetic energy flow to describe its motion. This can provide meaningful information, helping to identify and visualize the electromagnetic coupling path. The method has been applied to a set of canonical examples, such as coupling path and energy flow in wave guides. Fig. 2 shows the evolution of the trajectory of the energy parcel, corresponding to one of the TEM component waves of the TE01 mode in the rectangular waveguide. The trajectories reveal a characteristic zig-zag pattern, which agrees with the theoretical understanding of wave propagation in the waveguides. The unwanted coupling inside a router is used to illustrate the usefulness of the method for a practical problem. A photo of the router is shown in Fig. 3. Full wave simulation with FEM solver is used to obtain the fields for the trajectory calculation. It is difficult and unnecessary to model everything in the system. The noisy memory IC, the WLAN related components, and the large metallic structures are included in the simplified numerical model built and solved in HFSS as shown in Fig. 4. As shown in fig. 5 and fig. 6: The energy is coupled to the coax cable outside, then it by-passes a ferrite bead which has lost its main EMC properties at 2.4GHz. Further, the energy by-passes a lambda/4 choke. This choke had been slightly off-tune due to design problems in the WiFi router. The example shows the applicability of the method to real problems. However, a full field solution is needed with sufficient accuracy. This requires to obtain an impression of possible coupling paths prior to the creation of a numerical model, as it is not possible to include all details of a product into the numerical modeling. After the full wave simulation the E and H fields are obtained at every point in space. The visualization of the coupling is performed by backtracking the energy flow from the receive IC (Fig. 6), along the inside of the coax cable to the Wifi antenna and continuing the back tracking of the energy flow, which is guided by currents on the outside of the coax. Finally, the back tracking finds the source, which is the noisy memory IC. As of November 2013 detailed description of the methodology are under review for the IEEE Transactions on EMC in a two paper series.