Study of the effectiveness of spatially EM-diverse redundant systems under reverberation room conditions

In the most recent IET Guide on ElectroMagnetic Compatibiliy (EMC) for Functional Safety [1], diverse redundancy is indicated as one of the techniques to cope with the effects ElectroMagnetic (EM) disturbances within safety-or mission-critical applications. Unfortunately, up to now, little or no research is available on how to implement such EM-diverse redundant system. This paper studies the effectiveness of spatial diversity to cope with EM disturbances caused by strong incident fields under reverberation room conditions. Here, reverberation room conditions refers to the situation where multiple plane waves are incident onto the system-under-study, each with a random angle-of-incidence, polarization and phase. Four different geometries are compared: a non-redundant system comprising a single trace on a PCB, a redundant system comprising three parallel traces on a single PCB, a redundant system comprising three non-parallel traces on a single PCB, and a redundant system comprising three differently oriented PCBs. A reciprocity-based technique is used to efficiently calculate the induced voltages and the resulting bit error probability in the different geometries. It is shown that only when using three differently oriented PCBs a significant reduction in the bit error probability is obtained.