This paper introduces an innovative siliconmicromachined antenna operating in the 500-750 GHz range, based on an optimized elliptical Fresnel Zone Plate Lens (FZPL) design. The antenna radiates a circularly polarized wavefront without additional phase compensation components. With a gain of 25.7 dBi and a 15 dB return loss over the whole waveguide band, this low-profile, compact antenna presents a promising solution for upcoming wideband THz communication applications. This work highlights the potential of silicon micromachining in achieving high-performance antennas with a compact footprint in the THz bands.