A methodology to synthesize a low-profile composite-dielectric phase-correcting structure (CD PCS) is presented. The CD PCS, in function, is similar to an all-dielectric varying-height PCS and transforms a nonuniform aperture phase distribution of a low-gain antenna to a nearly uniform phase distribution. The methodology is aimed at reducing the maximum height of all-dielectric PCSs by using a combination of commercially available transmissive dielectric materials. The principle of operation has been demonstrated by designing a CD PCS using two dielectric materials. A higher permittivity dielectric material is used in the central region of the CD PCS, which requires a larger phase delay, while a lower permittivity dielectric material is used in the outer region, which requires a smaller phase delay. The height of the CD PCS is 43\% less and its weight is 25\% less than the single-dielectric PCS, but both have similar radiation performance.