The results of new two-frequency two-vibrator radiators researches are presented. It is shown that under certain ratios of operational frequencies there is a current cut-off effect between vibrators that provides optimum quasiisotropic patterns. The absence of this effect in a few ratios of frequencies does not allow to receive necessary weak-directional patterns for mobile radio means of continuous communication. The way of improving the directional characteristics of two-frequency antennas for any ratio of operational frequencies is proposed. The outcomes of researches are obtained by methods of integral equations and equivalent lines.