An on-chip integrated antenna oscillator-transmitter at 66GHz 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 7.6dBi and a low phase noise of -114dBc/Hz at 10MHz offset at 9mW power consumption. The figure of merit (FOM) of the VCO is -181dBc/Hz at 10MHz offset. The measured receiver power is -38dBm at a separated distance of 90cm at 66GHz. The fabricated oscillator-transmitter occupies a compact size of 0.61mm 2.