Flat-base broadband multibeam Luneburg lens for wide-angle scan

Abstract

In this paper, we present the design of a flat-base Luneburg type of lens antenna, designed for wide-angle scan. The antenna consists of a 11-layer lens, fed at its base by a 6×6$ 6 \times 6 $ array of waveguides. The lens is broadband and has a high aperture efficiency, only 1 dB below that of a reference aperture antenna with uniform amplitude and phase distributions. Its sidelobe level is –21 dB at boresight and –13 dB when the scan angle is 64∘$ 64^{\circ } $. It shows good performance when compared to the flat Luneburg lens previously reported in the literature, in terms of gain, scan capability, as well as ease of fabrication. It is shown to have the capability of producing multiple beams simultaneously, multiple angle, scan capability. Two different methodologies have been used to design the 6×6$ 6 \times 6 $ feed array of waveguides for the lens. The first of these utilizes a conventional perfect electric conductor waveguide, while the second employs materials for the guided wave region that has a high permittivity at frequencies at which metals become lossy and plasmonic. The performance of the lens has been investigated in this paper for both of these feed array designs.