We propose here a mathematical model of planning the measurements of submicron aerosol size spectrum developed to fit a mesh-type diffusion battery technique in application to the case of an aerosol with a single-mode size-distribution function. The technique proposed enables one to numerically determine an optimal number of meshes. When making computer simulations of locally optimal plans of measurements we have used some realistic parameters of the atmospheric aerosol size spectra. Based on modeling results we have constructed some analytical approximations of the observation plans.