A Focal Curve Design Method for Rotman Lenses With Wider Angular Scanning Range

This letter describes a novel focal curve design method for two-dimensional Rotman lenses. The proposed design method offers some additional degrees of freedom in the design of such beamformers and enables to extend significantly their angular scanning range, providing a solution to overcome the resulting focal arc and inner focal lens contour obstruction. A specific design, based on a phase-only model, is described, and numerical results are discussed. Good scanning performance over a very wide angle (± 50°) is demonstrated with phase-aberrations one order of magnitude lower than those of an equivalent standard Rotman lens. This improved beamformer design is of interest for low Earth orbit communication satellite antennas with a field-of-view ranging typically from ±40° to ±60°.