Fractional Luneburg Lens Antenna

The properties of a unit-fraction section of a spherical Luneburg lens, with two backing ground planes intersecting at the spherical lens´s axis, have been evaluated and compared to experimental results. Compared to a full Luneburg lens, the advantage of using a fraction of a Luneburg lens is the reduced weight of the antenna. This reduction is achieved at the expense of the scanning range of the antenna. An analytical expression relating the size of the ground plane to the scanning range is derived. The measured radiation patterns, gain, and scan loss of a hemispherical and of a quarter-sphere lens antenna are presented. The effects of the ground planes on the S parameters of the feed antenna are discussed, and simulated results are compared with measured results.