Near-field measurement is a methodological approach used to characterize physical fields, such as electromagnetic, acoustic, or optical, at distances very close to their source or a scattering object. This technique investigates the complex spatial distribution and behavior of fields within the region where the reactive or non-propagating components are significant and wavefronts exhibit substantial curvature, distinct from the propagating far field. Its key characteristics include the requirement for close proximity, often involving scanning or array techniques to capture detailed spatial variations. The significance of near-field measurement lies in providing detailed insights into the properties and mechanisms of sources, enabling accurate source reconstruction, and facilitating the prediction of far-field radiation patterns or scattering properties from comprehensive near-field data.