The investigation of Embedded System Electromagnetic Radiation by using Automatic Near-Field Measurements

Abstract

Electromagnetic interference (EMI) is increasingly becoming a major topic of concern in the electronic world. In the meanwhile, equipment designers need to do more with electromagnetic incompatibility than just make the systems operate. Electronic devices must be implemented to work in the real world without polluting the environment and to make standardized tests to comply with government electromagnetic compatibility regulations. Hence, the major design objective should be electromagnetic compatibility. The main purpose of this thesis is to investigate electromagnetic interference of different embedded system by using near-field probes. The main equipment used are an EMC scanner and an anechoic chamber (Bilog antenna) for measuring the EMI of different self-made loop antennas. This thesis aims to show how the electronic products easily break the limit level if there are some design faults. The main attention is to design a loop antenna and measure it with far-field and near-field probes and to investigate electromagnetic radiation at a certain point and frequency. The test is completed in far-field in which it is very difficult for the designers to spot the origin of interference. Comparatively, near-field measurements spot the radiation area. The near-field probes are used to complete the measurements in near-field which are very small in size. To get a specific result, smaller probes were used, since they locate a particular source of RF fields. According to the measurement results of this thesis, the near-field probe is the more efficient way of finding the interference.