The present invention provides a radio frequency (RF) antenna device (140) for applying an RF field to an examination space (116) of a magnetic resonance (MR) imaging system (110), whereby the RF antenna device (140) is provided having a tubular body, the RF antenna device (140) is segmented in its longitudinal direction (154), and each segment (162, 164) is provided with at least one activation port. The result is that each mode, corresponding to an activation port, may be controlled individually. Accordingly, the inhomogeneity of the subject of interest in this direction, i.e. in the longitudinal direction of the RF antenna device, can directly be addressed. There are different ways to build up a z- segmented RF antenna device.
