Ka-Band Multiple Feed per Beam Focal Array Using Interleaved Couplers

International audienceIn this paper, an original focal array for multibeam antenna is presented. It is based on Multiple Feed per Beam geometry. Each beam is produced by a cluster of feed horns illuminating a parabolic reflector. Three adjacent clusters of the focal array overlap for enhancing the illumination performance within the size-constrained array lattice. The Beam-Forming Network is the key component and drives the overall performance of the radiating structure. It is composed of tri-dimensional interleaved couplers made of circular waveguides and interconnected by thin radial rectangular waveguides. The design, manufacturing and measurement of a Ka-band Multiple Feed per Beam focal array are reported. It is composed of 31 feed horns displayed in 7 clusters, for a global size of about 6λd where λd denotes the free-space wavelength at the lowest operating frequency. The realized gain is higher by 1dB than the gain provided by the Single Feed per Beam focal array having analogous size