Monopoli, TomasTomasMonopoliWu, XinglongXinglongWuYang, ChengChengYangSchuster, ChristianChristianSchusterPignari, Sergio AmedeoSergio AmedeoPignariWolf, JohannesJohannesWolfGrassi, FlaviaFlaviaGrassi2026-04-152026-04-152026-03-31IEEE Transactions on Electromagnetic Compatibility (in Press): (2026)https://hdl.handle.net/11420/62711Identifying critical frequencies of a device under test (DUT) from its near-field scans is an essential step in integrating near-field scanning into electromagnetic compatibility (EMC) testing. Indeed, real electronic devices may exhibit radiated emissions at multiple frequencies, which are unknown a priori. To this end, three computational methods are introduced to identify the frequencies at which the DUT is radiating: the space-filled spectrogram analysis, the grey level co-occurrence matrix approach, and spatial fast Fourier transform approach. Although a single general solution is not provided, each method leverages different properties of the measurements to extract significant features and identify frequencies of interest. Therefore, the choice of which method to apply depends on the characteristics of the DUT and on the requirements of the specific measurement campaign. The proposed methods are evaluated on a common dataset, assessing their computational efficiency, sensitivity to patterns, and robustness against noise. Case studies demonstrate their successful application in real-world scenarios and their comparative analysis provides insights into selecting the most appropriate approach for a specific application.en1558-187X2026Institute of Electrical and Electronics Engineers Inc.Infinitesimal dipole modelnear-field scanningprinted circuit boards (PCB)radiated emissionsspectral analysisNatural Sciences and Mathematics::537: Electricity and ElectronicsTechnology::600: TechnologyJournal Article10.1109/TEMC.2026.3673588