A radar device for the transmission of a signal in a frequency band. The radar device includes a control means and an oscillator. The input of the oscillator is connected to the control means by means of a converter. The oscillator is controllable by means of the control means for the generation of the signal. The signal is generated by means of the oscillator and can be picked up on an output of the oscillator. The radar device also includes at least one transmission aerial for the transmission of the signal being present at the output of the oscillator. The transmission aerial is connected to the output of the oscillator. At least one receiver channel is provided for the reception of a received signal and for the processing of the received signal and for the transmission of the processed received signal to the control means. The receiver channel has at least one receiving aerial and a mixer for the mixing of the received signal with the signal which is present at the output of the oscillator. The mixer is connected to the output of the oscillator, and the output of the oscillator is connected to an input of a switchable amplifier and the amplifier provides a signal at the output and transmits it to the at least one mixer. A wattmeter is provided, which monitors the signal at the output of the amplifier and transmits it to the control means.