Phase monitoring for multi-channel MR broadcast systems

The invention relates to a method and a magnetic resonance imaging system (101) using a multichannel transmission system to generate to be transmitted (TX coils, 106, 108) signals (RF1, RF2, RF3, RFn) for a plurality of transmit channels (SK1, SK2, SK3, SKn) with means for coupling (RK1, RK2, RK3, RKN) of signals (RF1, RF2, RF3, RFn) of different transmission channels (SK1, SK2, SK3, SKn) of a transmission chain (MCPU, RFPA, VALLEY, Sk1, 108) and Create from the transmission chain coupled out signals (Si) to inputs (E1, E2, E3, En) of a Butler matrix (Butler matrix), and with a Butler matrix that is arranged such that a link fitting at its inputs (E1, E2, E3, En) signals (RF1, RF2, RF3, RFn) of different transmission channels (SK1, SK2, SK3, SKn) is carried out in such a way that the amplitude of at outputs of the Butler matrix dispensable Butler matrix output signals (BA) depending on the relative phases of which the phases of signals (RF1, RF2, RF3, RFn) of different transmission channels (SK1, SK2, SK3, SKn) (at inputs E1, E2, E3, En) is the Butler matrix have mutually relatively, said Butler matrix output signals are input (BA) to inputs of a monitoring unit (amplitude supervision), which is adapted on the basis of amplitudes of the Butler matrix output signals (BA), the relative phases of the signals (RF1, RF2, RF3, RFn) to be determined.