This letter presents a transmitter for sub-THz radiation (up to 160GHz), which consists of a nonlinear transmission line (NLTL) and anextremely wideband (EWB) slot antenna on a silicon substrate of lowresistivity (10 Ohmscm). The fabrication was realized using a commercially available 65 nm CMOS process. On-wafer characterization of the whole transmitter, of the standalone EWB antenna and of the standalone NLTL is presented. Reflection measurements show that the standalone EWB antenna has a −10dB impedance bandwidth in the frequency bands 75-100 GHz and 220-325 GHz, which agrees very well with the simulation results. The simulated radiation patterns are also presented, indicating that the antenna has an ominidirectional radiation performance. The antenna shows also a maximum power gain of -9.5 dBi between 90 GHz and 120 GHz. The output power of the NLTL alone and of the NLTL integrated with the EWB antenna is measured up to 178GHz.