An array fed multibeam antenna using equal phase–shift active elements

A multibeam antenna allows a large communication capacity and is suitable for satellite-borne instrument. The present paper proposes a new array antenna with a reflector. The array is composed of active elements with equal phase shifts and is spatially fed by a multibeam horn. The array emits a spherical wave to a reflector. Its compact size fits satellite-borne instrument and at the same time a good quality is expected for the gain and the sidelobe properties. Optimal values of the parameters are theoretically determined for S band operation with array construction, array position, number of elements, and apertures, and the properties of this antenna are derived. It is theoretically predicted that the space feed gives rise to a uniform power distribution over the elements. This prediction has been experimentally verified with a 19-element array antenna. High power repeaters are no longer required and an arbitrary power distribution over the elements is readily realized.