Abstract: This paper presents a study on the spatial expansion characteristics resulting from the incomplete directional sensitivity of irregularity scattering, and constructs a theoretical model that describes how the range extension width varies with detection distance. Based on observational data from the Qujing VHF coherent radar, it systematically investigates the dependence of the range extension width on radar detection distance under the influence of atmospheric wind field drift. A comparative analysis of numerical simulations and measured results shows good consistency, verifying the accuracy and reliability of the proposed method in describing and analyzing the characteristics of ionospheric irregularities. This study reveals the range extension effect induced by wind field drift, providing a new physical mechanism and analytical perspective for explaining the height attenuation phenomenon of irregular echoes.