Smooth-walled spline-profile horn feed to enlarge compact antenna test range quiet zone

We report the use of an Smooth-Walled Spline-Profile (SWSP) horn shaped beam feed with pattern optimized to achieve maximum compact antenna test range (CATR) quiet zone (QZ) size for a given reflector dimension, thereby minimising the cost of a new systems or increasing the capacity of existing facilities. We illustrate the concept with a sector-shaped, single offset reflector CATR by examining the impact that this has on the amplitude taper and the amplitude and phase peak-to-peak ripple of the QZ. We demonstrate that a Smooth-Walled Spline-Profile horn feeding an un-serrated rim reflector can attain a useable QZ area exceeding 50 percent the size of the 350 wavelengths diameter main reflector. This represents an increase in QZ area of over 60 percent compared to a conventional corrugated horn feed. The Smooth-Walled Spline-Profile horn offers a QZ bandwidth of just 9 percent compared to the 23 percent of the corrugated horn but is considerably cheaper to manufacture.