Enhancing reflector aperture usage efficiency using a coaxial cavity antenna: Application to compact antenna test range
Aperture usage is one of the most important problem in reflector-based compact antenna test range(CATR). Single reflector CATR provides very low aperture usage, normally 30%, because of the effects of edge diffraction. In order to solve this problem, serrated edges and rolled edges are generally chosen along the reflector's edge to reduce the edge diffraction field inside quiet zone(QZ) of the CATR. Even if edge diffraction has been handled by edge treatment, the QZ utilization rate of single reflector CATR (< 50%) is still low. Big reflector is therefore required to produce large QZ, which increases processing difficulty and construction cost. All of this means it is imperative to study reflector aperture distribution function and then design suitable feed's radiation field. In this paper, the aperture power density function of a parabolic reflector fed by an ideal point is theoretically derived and accordingly a coaxial cavity horn feed is designed to make the power density function constant on parabolic aperture surface and then on the QZ aperture, which realizes high QZ usage of the single parabolic CATR.