Protecting circuitry from transient pulses, inter cable coupling, EMP, and HIRF is becoming more difficult as signal speeds increase and the environment they operate in becomes electronically harsher. Thankfully, ElectroMagnetic Consultants can simulate existing or new designs, and reccomend design changes to better protect your system. Lets look at a quick example of a PCB board that was having trouble operating in a high RF environment:

The above is an older multilayer PCB board that was imported from its .gerber file used during manoufacturing. The equivalent circuit was then designed from this .gerber file to model the connections between nodes. This is a painstaking task, but it works. In this case, decoupling capacitors seen in blue were already placed at problematic nodes to alleviate coupling issues.

Simulating for susceptibility on a PCB board can be done via direct pin injections, or by having an incident plane wave hit the board. Each case will yield unique results. In this example, the above waveform was injected into Pin1, just to see what happens as a result.

Above is the coupled waveform at an arbitrary pin, in this case Pin8. We can view see that not only is there the first component of the coupled waveform, but it appears again due to an open circuit reflection.

The resulting S81 parameters from the impulse into pin1 to pin8 are shown above. The 100MHz periodic coupling is a result of the FFT on the difference of the 10ns spikes in the S81 parameters, and is in line with what is expected.

Current densities and resulting E-Field distribution on the board can be viewed. As can be seen in the above plot, Pin1 obviously has a high time-averaged field strength since thats where we injected the signal. Suprisingly, this translates into higher fields on two traces running to high speed chips on the top of the board, which proved to be problematic. Results like this can only be found by using ElectroMagnetic Consultants to help you find solutions to your problems.