In order to make the antenna lightweight, this paper proposed a rectangular aperture stepped waveguide model working in the S band based on the 3D printing technology of ABS (Acrylonitrile Butadiene Styrene) plastic dielectric materials. The antenna incorporates a copper foil coating to provide the necessary electrical properties of a metal surface. The waveguide is fed by an SFT-50-3 semi-steel cable, and tested using an Agilent E8363B vector network analyzer. Experimental results demonstrate that the waveguide exhibits a reflection coefficient below −10 dB within the frequency range of 3.44 GHz to 3.8 GHz. Furthermore, to enhance the antenna’s gain, a prism lens with a trapezoidal axis cross-section printed in 3D using ABS plastic dielectric material is integrated at the waveguide’s front end. This configuration results in an increased gain of 6.41 dBi at 3.6 GHz. Compared to an all-metal model, the proposed antenna achieves an 86.5% reduction in weight while maintaining performance, making it suitable for various outdoor elevated antenna applications.