  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 6x6 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 degrees. 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 6x6 feed array of waveguides for the lens. The first of these
utilizes a conventional perfect electric conductor (PEC) waveguide, while the
second employs materials for the guided wave region that have 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.
