in a magnetic resonance system and operating method to set rf transmit parameters for a radio - frequency antenna that is excitable in a number of different , linearly independent transmit modes , the transmit antenna is successively excited in the different transmit modes , and , for each transmit mode in which the radio - frequency antenna is excited , a measured value distribution representing the radio - frequency field produced by the antenna in a defined volume area is determined . the homogeneity of the measured value distribution is evaluated with respect to a defined evaluation criterion and , if the evaluation criterion is satisfied , an optimized radio - frequency field distribution is determined from a combination of the measured value distributions up to that time . if the evaluation criterion is not fulfilled , the radio - frequency antenna is excited with a further transmit mode , and the procedure is repeated .