Reduction of Radiated Far-Field Emission and Susceptibility Using a Suspended Metal Loop

This paper presents the use of a small simple loop above a printed circuit board (PCB) to mitigate both the emission at 1 m (suggested by CISPR-25) and far-field susceptibility of a patch located on the PCB (used as an approximation for an integrated circuit). Loop parameters were optimized through full-wave simulations with respect to patch size, loop-to-PCB distance and operating frequency. This technique makes it possible, at the same time, to reduce emission by an average of 83%, and to decrease H-field coupling to the integrated circuit pins along with E-field amplitude, thus reducing susceptibility. This study clearly demonstrates the relevance of that simple and inexpensive approach for practical use in applications such as complex high-speed electronics including Systems-in-Package (SiP).