The existing technologies to reduce radar cross sections (RCSs) face numerous challenges in bandwidth expansion, and hence they have a long way to achieve full-band stealth. Additionally, the control mechanism of RCS reduction level is deficient. Here, we explore the root of problem to cause the bandwidth blind zones and propose a mathematical model to establish a mapping relation between the array factor (AF) in spatial domain and the RCS reduction in frequency domain. The mathematical model of full-band stealth for general oblique incidence is also constructed, which guides to design a diffuse artificial meta-structure (AMS) to validate the proposed model. Then we build a mathematical model based on the Chebyshev polynomial for RCS reductions with RdB equal-amplitude in controlling the scattering fields. As proof of principle, a diffuse AMS is designed, fabricated, and measured to reach the RCS reductions with preseted 21 dB equal-amplitude. The simulated and measured results are in good agreement, proving that the proposed theoretical models provide a cornerstone of the future advanced stealth technologies.