In the current work the multiband properties of the secondary radiation of low-sized pilotless vehicles by the method of electrody-namics modeling are investigated. The 3-D diagrams of RCS (scattering diagrams) are given. The frequency dependence of RCS in the range 50 MHz to 4 GHz is plotted. It is determined that with frequency increasing from one hand the maximum RCS is increas-ing and on the other hand the significant diagram sharpening in the incident field direction and the mirror direction taking place. As a result in high-frequency range the probability of direction coincidence for diagram maximum and a receiving antenna system is very low. To solve the problem of effective recognition of pilotless vehicle like Zala 421-12 it is recommended to use frequency range from 100 MHz to 1000 MHz including all resonance maximums. It is found out that for horizontal polarization of incident wave the RCS in the current frequency range is 5 times higher. It is shown that the simplification of the computer model of the pi-lotless vehicle by the elimination of the dielectric elements of the object gives the calculation time reduction up to 1.5 to 2.5 times. It is confirmed that the factors of the pilotless vehicle detection on the birds background concludes in relations of reflected signal amplitudes on different frequencies and polarizations.