The results of helical pitch measurements for the systems, in which induced antiferroelectric phase is observed, are presented. The bicomponent systems composed of the chiral three ring ester with partially fluorinated terminal alkyl chain 4-
2H-perfluorooctyloxy)biphenylate-4 and a member of homologous series of chiral three ring ester with protonated chain -4-(1-methylheptyloxycarbonyl)biphenyl-4 -yl 4-(3-alkanoyloxyprop-1-oxy)benzoates were investigated. The influence of alkyl chain length and the concentration of the hydrogenous component on the induction and helical pitch are discussed. The increase of concentration of a component with the alkyl chain causes the increase of helical pitch inferro and antiferroelectric phase. The increase of alkyl chain length causes the lengthening of helical pitch in ferroelectric phase and shortening of it in antiferroelectric phase.