The authors demonstrated a free-standing 74mm diameter hyperbolic silicon lens in a record low 0.27 focal number configuration with an advanced, optimized four-layer leaky wave (LW) feed to efficiently illuminated the lens. Silicon micromachining techniques limited the permittivity for the optimization of each LW feed strata, and this reduced the calculated lens aperture efficiency slightly in the feed simulations. This practical innovative antenna design with low mass, low profile, high-gain and wide bandwidth uniquely facilitates THz spectroscopy on ultrasmall platforms.