A planar reflectarray antenna at150 GHz with sub-wavelength elements on a λ/4 grid is proposed, designed and tested. The unit-element consist of a two-layer stack-up with square patches. A maximum phase amplitude of 300◦ is achieved. The reflectarray antenna is composed of 52441 unit-elements and realized in PCB technology. An angle of arrival of 60◦ is applied. An angle of departure of 0◦ is achieved with a peak gain of 26.2 dBi in the measurement. The results demonstrate the scalibility of PCB technology for reflectarray antennas to D-Band applications. With respect to Intelligent Reflective Surfaces (IRS), the present prototype can be evaluated as a one-state reference and therefore provide measured data to be incorporated in 6G communication channel simulations.