The homologous series of 4-isothiocyanatophenyl 4-(trans-4-alkylcyclohexyl)benzoates (with n-alkyl chain from ethyl to dodecyl) were synthesized and their phase transition temperatures and enthalpies, smectic layer spacing and dielectric permittivity were measured. It was observed that the smectic A, layer spacing is expanding from d/1 similar to 1 to d/1 similar to 1.1 when the alkyl chain increases from butyl to dodecyl. It was proposed to term the smectic A(1) with d/1>1 as the enhanced smectic A(1) (A(1c)).