Abstract: This paper proposes a heterogeneous substrate that can be applied to flexible antennas. The substrate is fabricated using PolyJet 3D printer. Heterogeneous substrates are composed of digital ABSs which are evenly distributed in the flexible material Agilus. By changing the volume ratio of the digital ABS, the mechanical and dielectric properties of the heterogeneous substrate can be adjusted. Firstly, the dielectric properties of the heterogeneous substrate are estimated by the effective medium approximation theory, and the dimensions of the heterogeneous substrate and the digital ABSs with different volume ratio are designed. Then, the hybrid printing is carried out using PolyJet according to the designed model, and the dielectric properties of the heterogeneous substrate are characterized through the ring resonator theory. Finally, a patch antenna is fabricated on the heterogeneous substrate and the performance of the antenna is tested under different bending conditions.