Accurate testing of low cross-polar antennas in Compact Antenna Test Ranges (CATR) requires a quiet zone with high polarization purity. In the testing of electrically large antennas fitted to large platforms this requirement is often the main motivation to choose the more complex and thus expensive compensated dual reflector CATR as opposed to the simpler and cheaper single reflector CATR.
With the CXR feed, MVG has developed and validated a new plug-and-play component that performs cross-polar reduction, similarly to the second reflector in dual compensated CATR.
The CXR feed has been conceived to significantly improve the cross-polar accuracy of side/corner-fed single reflector systems but is equally suitable for dual cylindrical reflector systems.
The concept behind the CXR feed is the cancellation of the Geometrical Optics (GO) cross-polar component induced by any offset reflector by means of an innovative architecture providing conjugate field matching over a bandwidth of 1.5:1.
While maintaining all other quiet zone performance parameters, the feed provides uniform low cross-polarization levels, typically 40dB cross-polar discrimination. This is directly translated to an improvement of the uncertainty budget of the system.
The dual linear polarization of the CXR facilitates the measurement process. It shortens the feed alignment time and can greatly reduce the measurement time.
Talking about this latest development, Lars Jacob Foged, MVG’s Scientific Director explains: “High polarisation purity of the test area undoubtedly impacts measurement accuracy. This novel feed concept is a breakthrough in CATR systems as it extends their measurement capabilities beyond the traditional limitations. And this at the affordable cost of a feed replacement.”