The dielectric spectroscopy of an antiferroelectric liquid crystal (S)-4(-1-methylheptyloxycarbonyl) phenyl-4'-(6-pentanoyloxyhex-1-oxy) biphenyl-4-carboxylate for its homogeneous anchoring has been carried out for 10 mu m and 4 mu m cell thicknesses. This study suggests that the dielectric strength of Goldstone mode of the SmC* phase is significantly diminished from similar to 195 to similar to 69, whereas its relaxation frequency is increased from similar to 2 kHz to similar to 4 kHz from the higher to lower cell thickness. Alternatively, these parameters for the soft mode detected in the SmA* phase and for the two antiferroelectric relaxation modes detected in the SmCA* phase do not show any appreciable change with the cell thickness.