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IEEE Dallas EMC Society

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Presentation on theme: "IEEE Dallas EMC Society"— Presentation transcript:

1 IEEE Dallas EMC Society
System Level EMC Simulation Using the TLM Method This is the latest version of the FLO/EMC sales presentation suitable for use in conjunction with the ‘official’ Flomerics sales intro presentation. It contains ‘notes’ pages to assist the presenter (comments in italics are information for the presenter). Please direct question, comments and/or criticisms to: Fred German Electromagnetics Product Manager Phone: In most sales situations, a subset of this material may be used. Here, I try to provide some guidance as to which sections of slides I use in various situations. The following summarizes (via slide #) how I usually present the material. Slides not included below are almost always included in the presentation. Slides 14-22: These slides are intended as simple examples of the items that are bulletized in slide 13. In some cases, the bullet items are covered during the live FLO/EMC demo and so these can be eliminated from the presentation in order to reduce the total time required. It is recommended to include these simple examples particularly when presenting to an audience that is not well-versed in EMC design (e.g., FLOTHERM users). Slides 34-36: These slides are hidden in the presentation and are usually not included in the interest of time, but they are good validation examples that can be used effectively Slides 25-27: These slides are usually not included in the main presentation unless speaking to an audience particularly versed in computational electromagnetics or if this material has been specifically requested. David Johns

2 What is FLO/EMC…? The first electromagnetic field simulator developed specifically for system-level EMC design in the electronics industry Enables EMC problems to be identified and managed in the early stages of design Good for investigating radiated & conducted emissions, immunity (susceptibility), ESD and crosstalk problems: Enclosures & EMI shields Interfaces between boards and chassis Cables and EMI filters Unintentional antennas! (heat sinks etc.) Based on the 3D Transmission-Line Matrix (TLM) Method FLO/EMC facilitates exploring improvements to containment and immunity designs for system and sub-system enclosures and investigate tradeoffs between thermal & EMC design needs. FLO/EMC helps in identifying specific mechanisms for unwanted electromagnetic transmission through chassis and sub-systems.  These include: Cavity resonances Radiation through slots, seams, vents and other chassis openings Conducted emissions through cables Coupling to/from heat sinks and other components Unintentional wave guides inherent to optical components, displays, LEDs and other chassis mounted components Etc. In the following slides, specific examples will be presented.

3 TLM Method 3D space-volume divided into nodes (10th wavelength)
X Y Z Ey= ½ (V3i + V4i + V8i + V11i ) / DY 3D space-volume divided into nodes (10th wavelength) Each node is a 12-port transmission-line junction Scattering at the nodes models coupling between E and H fields Transient E and H fields are calculated from combinations of voltages and currents on the transmission lines Spectrum found by FFT

4 TLM Coupling Matrix Incident Pulses Vik Reflected Pulses Vrk+1 S = ½
YX ZY XY ZX YZ XZ 1 2 3 4 5 6 7 8 9 10 11 12 -1 Incident Pulses Vik Reflected Pulses Vrk+1 S = ½ Ey= ½ (V3i + V4i + V8i + V11i ) / w

5 Wave Propagation, Time 0 1

6 Wave Propagation, Time 1 -0.5 0.5

7 Wave Propagation, Time 2 -0.5 0.5 0.25 -0.25

8 Wave Propagation, Time 3 0.25 -0.25 0.125 0.375 -0.125 -0.375

9 Complexity of EMC Analysis
connectors seams air vents FLO/EMC facilitates exploring improvements to containment and immunity designs for system and sub-system enclosures and investigate tradeoffs between thermal & EMC design needs. FLO/EMC helps in identifying specific mechanisms for unwanted electromagnetic transmission through chassis and sub-systems.  These include: Cavity resonances Radiation through slots, seams, vents and other chassis openings Conducted emissions through cables Coupling to/from heat sinks and other components Unintentional wave guides inherent to optical components, displays, LEDs and other chassis mounted components Etc. In the following slides, specific examples will be presented. Accurate modeling requires geometric detail A long narrow seam may be a good antenna! Meshing the detail is computationally impractical Compact vent model

10 FLO/EMC Smart Parts TLM method uses a TL-Matrix to model fields.
Other TL’s & lumped-circuit models can be connected into the matrix. Arrays of small holes are often necessary to provide adequate thermal ventilation/cooling. Apertures increase emissions and decrease shielding effectiveness of the box. Low-frequency fields are evanescent near the apertures. Extremely fine grid would be required to model the exponential decay. FLO/EMC overcomes this difficulty by inserting a “smart part” into the grid.

11 Air vent smart part For a thin panel TEM transmission can be modelled by a shunt inductor. L is like a short at DC, but allows high freq. transmission. TEM For a thick panel the additional electric field inside the aperture can be modelled by a shunt capacitor L models the current flow along the edges of the apertures C models the electric field stored inside the apertures.

12 Transmission dependence on aperture shape and size, coverage and depth – empirical results
Fine TLM mesh of single aperture used to calculate dependence of Transmission on aperture shape and size, coverage and depth Fit L,C air vent parameters to the Transmission results at two frequencies - 10% and 80% of aperture cut-off frequency

13 Air Vent Implementation
Inductor modelled by short-circuit transmission line Capacitor modelled by open-circuit transmission line

14 Validation - Plane Wave
1D propagation through an array of circular apertures (depth equal to diameter) The fine TLM mesh and air vent model give the same results at 10% and 80% of aperture cut-off frequency

15 Validation - Emission r = 10.0 mm p = 5.0 mm t = 1.65 mm N = 252
[M.Li et al,’EMI…’,IEEE Trans EMC, Vol. 42, No. 3, p265,2000] r = 10.0 mm p = 5.0 mm t = 1.65 mm N = 252 a = 50 mm b = 20 mm c = 40 mm d = 10 mm

16 Run time on Dual Pentium Xeon with 3 GHz clock rate
Air vent model 3 min

17 Enclosure with thick walls
r = mm p = 0.69 mm t = mm N = 45 a = 100 mm b = 80 mm c = 15 mm

18 Run time on Dual Xeon with 3 GHz clock rate
Fine TLM mesh Air vent model 2.5 hours 4 min

19 Enclosure with vents & slots
r = mm p = 0.69 mm t = mm N = 45 a = 50 mm b = 20 mm c = 40 mm l = mm w = mm t = mm

20 Air vents and slots 3m from air vent 3m from slot
Run time on Dual Xeon with 3 GHz clock fine TLM mesh compact models 2.5 hours 3 min

21 Multi-Wire Smart Part cable connector pins Multi-conductor TL models of wires are connected into the TLM grid Full coupling between wires and fields Supports splits, bends, multi-way connections, circuit terminations and ports Compact vent model FLO/EMC facilitates exploring improvements to containment and immunity designs for system and sub-system enclosures and investigate tradeoffs between thermal & EMC design needs. FLO/EMC helps in identifying specific mechanisms for unwanted electromagnetic transmission through chassis and sub-systems.  These include: Cavity resonances Radiation through slots, seams, vents and other chassis openings Conducted emissions through cables Coupling to/from heat sinks and other components Unintentional wave guides inherent to optical components, displays, LEDs and other chassis mounted components Etc. In the following slides, specific examples will be presented.

22 Near Field Scan Smart Part
Emissions FLO/EMC facilitates exploring improvements to containment and immunity designs for system and sub-system enclosures and investigate tradeoffs between thermal & EMC design needs. FLO/EMC helps in identifying specific mechanisms for unwanted electromagnetic transmission through chassis and sub-systems.  These include: Cavity resonances Radiation through slots, seams, vents and other chassis openings Conducted emissions through cables Coupling to/from heat sinks and other components Unintentional wave guides inherent to optical components, displays, LEDs and other chassis mounted components Etc. In the following slides, specific examples will be presented. Pre-determined near-field scans over entire boards or regions/components can be imported and applied as distributed frequency-dependent (time-varying) sources Ideal for PCB with 1 or 2 layers where radiation from “exposed” nets may be important

23 TLM References 1. Johns P. B. & Beurle R. L., ‘ Numerical Solution of 2-Dimensional Scattering Problems Using a Transmission-Line Matrix’, Proc. IEE, Vol. 118, No. 9, Sept 1971.  2. Akhtarzad, S. and Johns, P. B., ‘The solution of Maxwell’s equations in three space dimensions and time by the TLM method of numerical analysis’, Proceedings IEE 122, 12, p , December 1975.  3. Johns P. B., ‘A symmetrical condensed node for the TLM method’, IEEE Trans. Microwave Theory and Techniques, Vol. MTT-35, No. 4, pp , 1987. 4. Christopoulos C., ‘The Transmission-Line Modeling Method: TLM’, IEEE Press and Oxford University Press, A volume in the IEEE/OUP Series on Electromagnetic Wave Theory ISBN

24 If you have any questions or comments, we welcome your feedback !
Please visit the FLO/EMC web site at and us at Flomerics Inc. 257 Turnpike Road, Suite 100 Southborough MA 01772 Tel: (508) Flomerics Inc Old Ironsides Drive - #390 Santa Clara, CA Tel:(408) Flomerics Inc Clayton Lane, Suite 525W Austin, TX Tel: (512) Flomerics Inc. 410 South Melrose Drive, Suite 102, Vista, CA 92083 Tel: (760)


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