Three-Dimensional Vehicular Ignition Noise Radiation Patterns

A new test facility has been established for measuring the three-dimensional radiation patterns of electromagnetic interference generated by automobile ignition systems. Much of the uncertainty commonly associated with ignition noise measurements has been removed through the use of special measurement procedures and the application of computer data processing. The patterns resulting from this study dramatically illustrate the lobing structure of ignition noise radiation and explain the difficulties encountered when attempting to characterize it by sampling at only a few spatial locations.