To give a true measurement of an antennas performance phase stable measurements between the channels of a multi-channel antenna are a necessity. It is well understood that the mechanical movement of Radio Frequency (RF) cables alters the magnitude and phase of the signal. This paper presents measurements taken on a moving positioner in an anechoic chamber to assess best practice on how to measure multi-channel antennas with minimal phase errors between channels. S11 measurements are presented for different measurement scenarios (sweep or point-to-point) and different hardware configurations (the use of a multi-channel Vector Network Analyser (VNA) and multiple co-axial cables, or a two channel VNA, multiplexer and a single co-axial cable). Results show the most phase stable measurements are taken in a point-to-point manor with a multiplexer behind the antenna and a single co-axial cable running to a VNA.