An on-chip integrated antenna oscillator-transmitter at 66 GHz for frequency modulation short range transmission is presented. The oscillator-transmitter comprises a high gain differential-fed linear tapered slot antenna and a low phase noise differential Darlington pair voltage controlled oscillator (VCO) with intrinsic junction varactors. The transmitter achieves a high antenna gain of 7.6 dBi and a low phase noise of ߝ 114 dBc/Hz at 10 MHz offset at 9 mW power consumption. The figure of merit (FOM) of the VCO is ߝ 181 dBc/Hz at 10 MHz offset. The measured receiver power is ߝ 38 dBm at a separated distance of 90 cm at 66 GHz. The fabricated oscillator-transmitter occupies a compact size of 0.61 mm2.