A Compact Antenna Test Range (CATR) is a type of range used for testing antenna systems at frequencies where obtaining Far-Field spacing to the AUT would be impractical using traditional free space methods. A CATR, based on a single reflector, uses a source antenna which radiates a spherical wave front, and one reflector to collimate the radiated spherical wave front into a planar wave front within the desired test zone. A CATR is used for microwave and millimetre wave frequencies where the 2D2 /λ far-field distance is large, such as with high-gain reflector antennas.