Susceptibility Mapping

The concept of susceptibility mapping is introduced. A susceptibility map is created by scanning a signal source (loop antenna) over a circuit board, and at each point raising the signal level until failure occurs. Maps obtained with CW EM1 reveal design problems such as tight circuit timing or small static noise margins. They also reveal manufacturing problems, such as bad contacts and faulty chips. This leads to the concept of electromagnetic stress testing. Maps obtained with transient EM1 require tight synchronization for repeatability and are useful in studying specific software-dependent failures.