Here, we present the design and experimental directional coupler operating in the low THz frequency range of 60-330 GHz enabled by silicon micromachining technology. Macromachining offers very low losses and high performance due to absence of metals and high precision of manufactured devices. This technology allows fabrication in a single etching step and provides a method for engineering the coupling coefficient. The fabrication of such high-performance directional couplers in the sub-THz frequency range is described, and the measurement results of the fabricated prototypes are reported and discussed.