A design procedure for classical offset Dragonian antennas with circular apertures

Numerous antenna applications (e.g., remote sensing, radar, and communication) require compact antennas capable of providing a high gain over a wide field of view. Although high performance over a moderate field of view can be achieved with conventional classical offset dual-reflector geometries, some applications require performances unattainable with these antennas. For such cases, the classical offset Dragonian antenna might provide the required improved performance. This antenna employs a paraboloidal main reflector illuminated by a concave hyperbolical subreflector, and its performance has been confirmed. Although Dragonian antennas have been around for more than two decades, to the authors´ best knowledge an electrical design methodology is not yet available for them. In this paper a convenient step-by-step design procedure for electrically optimized (i.e., zero geometrical-optics cross polarization and minimum spillover) classical offset Dragonian antennas with a circular aperture is presented. The procedure starts from readily available mechanical parameters and straightforwardly yields an optimum classical design.