Array-fed reconfigurable reflector for spacecraft applications

The paper describes a new type of reconfigurable reflector antenna for spacecraft applications, in which both the reflector shape and the excitation of a small array feed combine to offer maximum coverage flexibility. To create a reconfigurable continental coverage, the array is excited to produce a suitably tapered, circularly symmetric pattern, and the shape of the mesh reflector adjusted to yield the appropriate secondary radiation pattern. When spot beams are required within the coverage region, the mesh reflector is configured as a paraboloid, and individual elements or local clusters excited within the array. The results of a theoretical study are described which involve a representative 50 lambda reflector. The comparison between experiment and theory is made using a prototype mesh reflector, whose performance with a single feed has been previously described, and whose centre operating frequency is 10 GHz. The antenna is fed from a 19-element array of small dominant-mode conical horns. Generally, excellent agreement between theoretical predictions and experimental results is obtained.