A nuclear magnetic resonance apparatus which is capable of identifying either spectra or images of an examination subject uses a body resonator, such as a whole-body antenna, for transmitting radio frequency signals at a wave length .lambda. to induce nuclear magnetic resonance phenomena in the examination subject, and a surface coil for receiving the resulting nuclear magnetic resonance signals. For decoupling the body resonator from the surface coil, a .lambda./4 line is connected to the surface coil. A terminating end of the .lambda./4 line is short-circuited during emission of radio frequency pulses by the body resonator, and is opened during reception of nuclear magnetic resonance signals using the surface coil. An effective detuning of the body resonator is thus achieved during the reception event, and at the same time the transmission event is minimally influenced.