This work presents the design and characterization of a high-gain transmitting module including a two-channel 45-nm CMOS transmitter and a folded transmitarray antenna. The proposed architecture enables the reduction by a factor three of the antenna height and a significant enhancement of the efficiency with respect to similar state-of-art D-band modules. The performance of this compact implementation is compared to that of a system based on a standard transmitarray. The experiments prove that the folded transmitarray preserves the effective isotropic radiated power (28 dBm at 148 GHz) achieved by the bulkier standard transmitarray, over the operating band of the integrated circuit, spanning from 139.3 GHz to 156.6 GHz.