This application provides example signal processing methods, media, and apparatuses. One example method includes obtaining a scattering parameter matrix of passive echoes in an antenna system by a network device. The m virtual user directions are determined by the network device based on the scattering parameter matrix of the passive echoes, where the m virtual user directions are m directions in which total signal strength of the passive echoes is highest, and m is a positive integer. A target beam is formed based on n real user directions and the m virtual user directions, where one or more nulls of the target beam are aligned with the m virtual user directions, n is a positive integer, and n+m≤k.