Maximum Radiated Emissions Calculator

This project is an extension of the EMC Expert System project that began 18 years ago with the formation of the UMR EMC Expert System Consortium at the University of Missouri-Rolla. It is based on the concept that all radiated EMI problems must have a source, an antenna, and a coupling path. Typical printed circuit board layouts have readily identifiable sources and antennas. The number of potential source/coupling-path/antenna combinations is large, but each combination can be readily identified by a computer with access to both the board layout and component information.

Precise calculations of the radiation from printed circuit boards are not possible due to the large number of unknown quantities in a realistic product design (e.g. enclosure and cable geometries, statistical variations in components and materials, etc...). Nevertheless, precise calculations are not necessary, because nearly all of the source/coupling-path/antenna combinations on a well-designed board are incapable of producing enough radiation to exceed the EMI requirements. In fact, the goal any PCB layout should be to ensure that there are NO source/coupling-path/antenna combinations capable of producing emissions above the requirements.

The Maximum Radiated EMissions Calculator (MREMC) calculates the maximum possible radiated emissions that a particular source/coupling-path/antenna combination on a printed circuit board is capable of producing. For all unknown quantities, the worst-case is assumed. For example, if there are attached cables or metallic enclosures with unknown geometries, the calculations are done as though these structures were optimally configured to maximize the radiated emissions. If digital signal rise-times are uncontrolled or otherwise unknown, the shortest possible rise-time is used for the calculations. Even with these worst-case assumptions, very few of the potential source/coupling-path/antenna combinations on a well-designed board will actually be capable of causing a radiated emissions problem. The goal of the MREMC algorithms is to quickly evaluate hundreds, or perhaps thousands, of combinations to quickly identify which components and structures on a board are potentially a problem.

The major algorithms used to identify and evaluate the source/coupling-path/antenna combinations on most digital or mixed-signal boards have been developed and validated on actual board designs. A web-based calculator has been created that engineers can use to evaluate these algorithms and/or apply them to structures on their own boards. The current effort for this project is focused in three key areas:

1. Identify a software partner to develop a robust tool that will automatically sort through the source/coupling-path/antenna combinations in a typical board layout, and apply the algorithms without requiring the user to manually input the relevant parameters.
2. Develop educational materials to help engineers understand how the tool works and how to best apply it to their designs.
3. Provide documentation precisely describing the algorithm operation to supplement the published papers that present and validate the algorithms in more general terms.

Web Links

Maximum Radiated Emissions Calculator

PCB EMC Expert System Web Page

Publications

1. T. Hubing, “Performance-based EMC Design using a Maximum Radiated Emissions Calculator,” Journal of Electromagnetic Engineering and Science, vol. 13, no. 4, Dec. 2013, pp. 199-207.
2. C. Zhu and T. Hubing, “Maximum Radiated Emission Calculator: Common-Mode EMI Algorithm,” Clemson Vehicular Electronics Laboratory Technical Report, CVEL-13-051, Dec. 23, 2013.
3. C. Zhu and T. Hubing, “Maximum Radiated Emission Calculator: Power Bus Algorithm,” Clemson Vehicular Electronics Laboratory Technical Report, CVEL-13-053, Oct. 12, 2013.
4. C. Zhu and T. Hubing, “Maximum Radiated Emission Calculator: Differential-Mode EMI Algorithm,” Clemson Vehicular Electronics Laboratory Technical Report, CVEL-13-052, Oct. 12, 2013.
5. T. Hubing, "Designing Automotive Components for Guaranteed Compliance with Electromagnetic Compatibility Requirements," In Compliance Magazine, May 2013.
6. X. He and T. Hubing, “A Closed-Form Expression for Estimating the Maximum Radiated Emissions from a Heatsink on a Printed Circuit Board,” IEEE Trans. on Electromagnetic Compatibility, vol. 54, no. 1, Feb. 2012, pp. 205-211.
7. C. Su and T. Hubing, “Calculating Radiated Emissions due to I/O Line Coupling on Printed Circuit Boards using the Imbalance Difference Method,” IEEE Trans. on Electromagnetic Compatibility, vol. 54, no. 1, Feb. 2012, pp. 212-217.
8. C. Su and T. Hubing, “Improvements to a Method for Estimating the Maximum Radiated Emissions from PCBs with Cables,” IEEE Trans. on Electromagnetic Compatibility, vol. 53, no. 4, Nov. 2011, pp. 1087-1091.
9. X. He, T. Hubing, H. Ke, N. Kobayashi, K. Morishita and T. Harada, “Calculation of Optimal Ground Post Resistance for Reducing Emissions from Chassis-Mounted Printed Circuit Boards,” IEEE Trans. on Electromagnetic Compatibility, vol. 53, no. 2, May 2011, pp. 475-481.
10. C. Su and T. Hubing, “Imbalance Difference Model for Common-Mode Radiation from Printed Circuit Boards,” IEEE Trans. on Electromagnetic Compatibility, vol. 53, no. 1, Feb. 2011, pp. 150-156.
11. X. Dong, H. Weng, D. G. Beetner, T. Hubing, “Approximation of Worst-Case Crosstalk at High Frequencies,” IEEE Trans. on Electromagnetic Compatibility, vol. 53, no. 1, Feb. 2011, pp. 202-208.
12. H. Zeng, H. Ke, G. Burbui and T. Hubing, “Determining the Maximum Allowable Power Bus Voltage to Ensure Compliance with a Given Radiated Emissions Specification,” IEEE Trans. on Electromagnetic Compatibility, vol. 51, no. 3, Aug. 2009, pp. 868-872.
13. S. Deng, T. Hubing and D. Beetner, “Estimating Maximum Radiated Emissions from Printed Circuit Boards with an Attached Cable,” IEEE Trans. on Electromagnetic Compatibility, vol. 50, no. 1, Feb. 2008, pp. 215-218.
14. Y. Fu and T. Hubing, “Analysis of Radiated Emissions from a Printed Circuit Board using Expert System Algorithms,” IEEE Trans. on Electromagnetic Compatibility, vol. 49, no. 1, Feb. 2007, pp. 68-75.
15. H. Shim and T. Hubing, “A Closed-Form Expression for Estimating Radiated Emissions from the Power Planes in a Populated Printed Circuit Board,”IEEE Trans. on Electromagnetic Compatibility, vol. 48, no. 1, Feb. 2006, pp. 74-81.
16. H. Shim and T. Hubing, “Model for Estimating Radiated Emissions from a Printed Circuit Board with Attached Cables Due to Voltage-Driven Sources,” IEEE Trans. on Electromagnetic Compatibility, vol. 47, no. 4, Nov. 2005, pp. 899-907.
17. H. Shim and T. Hubing, “Derivation of a Closed-Form Approximate Expression for the Self-Capacitance of a Printed Circuit Board Trace,” IEEE Trans. on Electromagnetic Compatibility, vol. 47, no. 4, Nov. 2005, pp. 1004-1008.
18. H. Shim, T. Hubing, T. Van Doren, R. DuBroff, J. Drewniak, D. Pommerenke and R. Kaires, “Expert System Algorithms for Identifying Radiated Emission Problems in Printed Circuit Boards,” Proc. of the 2004 IEEE International Symp. on Electromagnetic Compatibility, Santa Clara, CA, USA, Aug. 2004, pp. 57-62.
19. M. Xu and T. Hubing, “The Development of a Closed-Form Expression for the Input Impedance of Power-Return Plane Structures,”IEEE Trans. on Electromagnetic Compatibility, vol. 45, no. 3, Aug. 2003, pp. 478-485.
20. M. Xu and T. Hubing, “Estimating the Power Bus Impedance of Printed Circuit Boards with Embedded Capacitance,” IEEE Transactions on Advanced Packaging, vol. 25, no. 3, Aug. 2002, pp. 424-432.
21. M. Li, J. Drewniak, S. Radu, J. Nuebel, T. Hubing, R. DuBroff and T. Van Doren, “An EMI Estimate for Shielding-Enclosure Evaluation,” IEEE Trans. on Electromagnetic Compatibility, vol. 43, no. 3, Aug. 2001, pp. 295-304.
22. D. M. Hockanson, J. L. Drewniak, T. H. Hubing, T. P. Van Doren, F. Sha, C. W. Lam, and L. Rubin, "Quantifying EMI resulting from finite-impedance reference planes,"IEEE Trans. on Electromagnetic Compatibility, vol. 39, no. 4, Nov. 1997, pp. 286-297.
23. N. Kashyap, T. Hubing, J. Drewniak, and T. Van Doren, "An expert system for predicting radiated EMI from PCBs," Proc. of the 1997 IEEE International Symposium on Electromagnetic Compatibility, Austin, TX, Aug. 1997, pp. 444-449.
24. D. M. Hockanson, J. L. Drewniak, T. H. Hubing, T. P. Van Doren, F. Sha, and M. Wilhelm, "Investigation of Fundamental EMI Source Mechanisms Driving Common‑Mode Radiation from Printed Circuit Boards with Attached Cables," IEEE Trans. on Electromagnetic Compatibility, vol. 38, no. 4, Nov. 1996, pp. 557-566.
25. T. Hubing, J. Drewniak, T. Van Doren, and N. Kashyap, "An Expert System Approach to EMC Modeling," Proc. of the 1996 IEEE International Symposium on Electromagnetic Compatibility, Santa Clara, CA, Aug. 1996, pp. 200‑203.