Methods and circuit arrangements for operating multi-channel transmit/receive antenna devices or arrangements especially for use in magnetic resonance imaging (MRI) systems are disclosed, by which a fully independent control of complete multi-channel RF transmit and receive chains can be conducted in a flexible way and new options like RF shimming, transmit sensitivity encoding (TransmitSENSE), RF encoding, determination of S- or Z-matrix prior to spin echo measurements, calibration, SAR (specific absorption rate) reduction etc. can be utilized or improved.