This contribution presents the last developments of THz antenna arrays based on silicon micro-machined lenses for heterodyne receivers. The antenna proposed in this manuscript consists of a leaky waveguide feed that illuminates a shallow lens. It achieves high efficiencies and a good coupling to optical systems. Moreover it can be fabricated in parallel using silicon micro-machining techniques, obtaining an array of reduced size and mass to be used for space applications. The current focus of our research is the design of an antenna array operating at 1.9THz based on this antenna for astronomy applications.