A Rigorous Approach for the Radiated Emission Characterization Based on the Spherical Magnetic Field Scanning

Electromagnetic radiated emissions from antennas, printed circuit boards (PCBs), and electronic devices are becoming increasingly critical to today's IC electromagnetic compatibility and interference properties. In this paper, a rigorous characterization approach is proposed. The electromagnetic field sampling over a spherical testing surface is applied to obtain the radiated magnetic field of the device under test (DUT) placed at the center of the sampling region. Using the dyadic Green's function (DGF) and Huygens' principle, the transformation from the sampled spherical tangential field to the far field is directly computed without resorting to the conventional inverse algorithm. The DGF considers the existence of the perfect magnetic conductor sphere and can be represented by a series of spherical wave functions based on the Ohm-Rayleigh method and the scattering superposition technique. For the DUT placed on the infinite perfect electric conducting plane, only hemispherical field scanning is needed based on the image theory. To prove the validity and accuracy of the proposed approach, the electric far-field of Hertzian dipoles, microstrip patch antennas, and PCBs are benchmarked at the end of this paper.