Since several years, Electromagnetic (EM) radiations of ICs are considered as source of noise and interferences from an EM Compatibility (EMC) point-of-view. Electromagnetic interferences (EMI) are unwanted disturbances that affect digital circuits due to electromagnetic conduction or electromagnetic radiation emitted from an internal or external source. Today electromagnetic radiations of ICs also represent vulnerabilities for hardware security modules like smartcards. Recently, from a hardware security point of view, researchers, industrials and governmental agencies are focusing with strong interest on these radiations. This paper aims at introducing a pragmatic technique WGMSI (Weighted Global Magnitude Squared Incoherence) allowing localizing hardware security modules within the whole EM noise generated by the environment or other modules of the circuits.