Definition

EMI shielding uses conductive barriers to contain or exclude electromagnetic fields. PCB-level shielding includes: ground planes (blocks E-fields), edge plating (creates Faraday cage), embedded shields (copper pours around sensitive circuits), and shield cans (metal covers over RF sections). Effectiveness depends on material conductivity, aperture size (keep below λ/20), and ground continuity. Shielding prevents both emission (failing FCC/CE) and susceptibility (interference from external sources). RF circuits require careful shielding design - slots in ground planes act as slot antennas.