A
multiple input multiple output (
MIMO) calibration device (360) for calibrating a
phase relationship between at least two signals present on at least two
radio frequency (RF) paths
coupling a
wireless communication unit and the
MIMO calibration device (360) is described. The
MIMO calibration device (360) is operably coupleable via at least two RF paths between a
wireless communication unit and an antenna arrangement (219). The calibration device (360) comprises a
processing module (490) configured to: process a coupled amount of at least one first
signal from a first path operably coupleable to a first polarisation of the antenna arrangement (219) to determine at least one
pilot signal from said at least one first
signal; process a coupled amount of at least one second signal from a second path operably coupleable to at least one second polarisation feed of antenna arrangement (219), different to the first polarisation, to determine the at least one
pilot signal from said at least one second signal; and determine a first
phase relationship of the same
pilot signal between the at least two RF paths.