A D-band (110~170 GHz) transmitter module, based on a novel self-aligned microstrip-to-waveguide transition, was demonstrated. The simulated average insertion loss of the transition is about 0.6 dB and return loss is better than 10 dB during working band. A D-band transmitter module was developed using such transition with resistive mixer and multiplier chips. The transmitter module operates between 110~153 GHz and provides a peak saturated output power of -4.6 dBm at 150 GHz and with 13.5 GHz 3 dB bandwidth from 145.8 to 159.3 GHz. 3 Gb/s wireless communication with this module at 145 GHz was demonstrated with spectrum efficient 64-QAM modulation.