The invention relates to a vehicle radar system having an oscillator (5) which generates a high frequency signal, in time segments only and in accordance with a control signal, during functioning of the radar system. Said oscillator comprises a microwave diode, in particular a Gunn or impatt diode, accommodated inside a casing-like body. In accordance with the invention, at least one of the following elements: ohmic resistance, transistor or IC body, is so arranged as to be thermally bonded with the casing-like body or an element thermally connected thereto. Said component fulfils at least one other function beyond that of generating heat inside the radar system circuit. This guarantees that the oscillator begins to oscillate in sure and reliable manner, even at very low temperatures, and in particular in pulsed operating mode.