Lens Arrays for Increased Effective Isotropic Radiated Power and Reduced Focal Depth

This work proposes arrays of lenses as a means of reducing focal depth and increasing effective isotropic radiated power (EIRP), thereby addressing two of the fundamental limitations of single-lens antenna systems. We demonstrate the concept by numerically simulating lens arrays based upon the measured near-field data from a single 8“-diameter lens element (lenslet) and investigating arrays with between two and 32 lenses. Periodic aperture perturbations inherent in arrays of electrically-large elements cause grating lobes which must be addressed. We present lens array design guidelines which allow the angle of the fundamental grating lobe, and the range of the grating-lobe-free field-of-view (FoV), to be specified for a particular application. Methods are suggested to provide continuous beamscan within this FoV by way of time-delays or phase shifters and, if multiple lenslet feeds are properly weighted, the grating lobe can be reduced or eliminated.