Validation of automotive electromagnetic models

The problems of modelling the electromagnetic characteristics of vehicles and the experimental validation of such models are considered. The validity of the measurement methods that are applied in model validation exercises is of particular concern. A philosophy for approaching the validation of automotive electromagnetic models of realistic complexity is presented. Mathematical modelling of the key elements of the measurement processes is proposed as the only reliable mechanism for addressing these issues. Areas considered include: basic elements of numerical models; geometrical fidelity requirements for model elements; calibration and use of experimental transducers; the inclusion of cables in electromagnetic models; essential content for vehicle models. A number of practical measurement processes are also investigated using numerical methods, leading to recommendations for improved practices in: calibration of transducers for current measurement at high frequencies; measurement of radiated emissions from vehicles; identification of range requirements for simple methods of determining antenna gain and related characteristics in EMC test facilities. The impact of such measures on the success of model validation studies for automotive applications is demonstrated. It is concluded that experimental results are no less in need of validation than the numerical results that are, more conventionally, judged against them.