A novel characterization method of the radiation emission for electromagnetic compatibility

Conventionally the radiation emissions from PCB boards, electronic devices and antennas were characterized through the near field (NF) - far field (FF) transformation to find the equivalent sources. In this paper, a new methodology without NF-FF transformation is presented. Based on the uniqueness theorem, it only employs the measured tangential field over a spherical surface to rigorously characterize the outward radiation emission. The dyadic Green´s function for the perfect magnetic conductor (PMC) sphere is derived using spherical wave functions. Based on this dyadic Green´s function and integral equations, the NF-FF transformation is not necessary any more. To facilitate feasible near field measurements, only the tangential magnetic field is needed. As the proof of the concept, the radiations of Hertzian dipoles are analyzed. This approach can be directly used to characterize the radiation from PCBs and antennas.