As a special type of scatterer, an antenna exhibits electromagnetic scattering characteristics that are intrinsically linked to its fundamental radiation performance and the load state connected to its terminals. The electromagnetic scattering field of an antenna can generally be decomposed into two distinct components: structural mode scattering and antenna mode scattering. The structural mode scattering arises from the radiation of induced currents generated by incident radar waves on the antenna surface, which remains independent of the antenna's load conditions. However, when the antenna is loaded with an impedance-mismatched termination, the antenna mode scattering emerges as a secondary component resulting from the reflection of incident electromagnetic waves through the feeding network back into free space. Although under well-matched feed network conditions, antenna mode scattering usually shows a significantly lower amplitude than structural mode scattering, with the continuous upgrading of modern electronic warfare and the increasing stealth performance of targets, the precise measurement methods and effective suppression techniques of antenna mode scattering have become the focus of attention.