International audiencePredicting the immunity of electronic boards to radiated electromagnetic interference requires the computation of the coupling efficiency of an electromagnetic field to PCB traces. In the case of complex PCBs, full-wave electromagnetic solvers are convenient, yet at the expense of simulation time. Therefore, this paper introduces the extension of a modified Taylor-based analytical model to the case of traces terminated at one end by a non-characteristic impedance. This model makes it possible to determine the far-field-to-trace coupling using only a sum of closed-form equations. When applied to a shorted, meandered PCB trace, it was found to be as precise as 2.2 dB average absolute error with respect to GTEM measurements, which demonstrates its relevance for immunity prediction. Moreover, the full-wave simulation of this case study was validated using the extended model and found to be as precise as 1.4 dB average absolute error

In modern electronic products, the printed circuit board (PCB) traces may well form the dominant coupling path in radiated immunity problems. Therefore, an understanding of the designable parameters that influence the worst-case induced voltages can be of use to the PCB designer, together with rapid simulations. Therefore, a modified single (unmeshed) Taylor cell is combined with transmission line theory to predict the terminal voltages induced by a grazing, vertically polarized plane wave, incident on a multi-segment trace with arbitrary terminal impedances. The resulting model is closed-form and therefore suitable for rapid simulations. Furthermore, the model is geometrically approximated to provide understanding on how designable PCB parameters determine the worst-case induced voltage. Finally, the model is compared to measurement results.

Abstract-When performing immunity measurements through the 10 × 10-cm aperture of a GTEM (Gigahertz Transverse ElectroMagnetic) cell, its field uniformity is generally unknown. Yet, this (non)uniformity causes an error on test results. Measuring the field uniformity by taking a grid of samples would be timeconsuming. Even with such a measurement, it would be hard to predict the magnitude of this error in immunity measurement results. Therefore, another approach to the problem was taken: several imperfections of the GTEM cell were characterized simultaneously by measuring its S 11 -parameter. Then, the immunity of a DUT (Device Under Test) was simulated with the nominal GTEM field plus the first reflection. Entering this field model into the simulation corrected the major error in the 0.1-2.0 GHz range in some of our test cases, with no degradation in any case. Thanks to the speed of this method, it may be broadly applied, even only to quantify the effect of some of the GTEM's imperfections on a given immunity measurement.

As the frequency of functional signals and interfering fields is rising beyond 1 GHz, the immunity of integrated circuits (ICs) against these higher frequencies is interesting. To design test setups that mimic the real-world interference an IC may receive, the dominant coupling mechanism (radiation or conduction) needs to be known. We hypothesize that the dominant coupling mechanism is conduction for SOIC packages up to about 10 GHz. To challenge this hypothesis, the radiated immunity of a Printed Circuit Board (PCB) trace connected to a voltage regulator IC is predicted and measured. The radiated immunity is predicted to be the product of the fieldto-trace attenuation and the conducted immunity of the IC, thus neglecting the radiated immunity of the IC. As far as could be measured, the prediction correlated well with measurement, so the dominant-conduction hypothesis was not falsified with this case study.