Comparison of horizontal and vertical feed scanning based APC in a Compact Range

Feed based scanning Antenna Pattern Comparison (APC) is a method to improve antenna measurement accuracy similar to the well-known APC method. In contrast to APC, the transmit antenna (feed) is moved instead of the AUT. This is beneficial because moving the feed is in general easier than moving the AUT. Previous publications have shown that horizontal feed based scanning APC and APC show similar improvements. Feed based scanning APC can easily be extended to two dimensions and this paper presents a comparison between horizontal and vertical feed scanning directions. For the comparison the technique was applied to measurements of a high and a medium gain antenna as well as Quiet Zone (QZ) measurements in a single reflector Compact Antenna Test Range. It is shown that different feed scanning directions require different mechanical alignment capabilities. Furthermore, it is pointed out that depending on the measurement setup, the AUT characteristic and the underlying scattering sources, the feed scanning direction is a crucial parameter. Thus the feed scanning direction has to be considered in the usage of the feed based scanning APC technique.