  Modern communication systems will require antennas with adaptive
functionality which are able to modify their performance based on the
requirements of the channel. For example, mobile ad-hoc networks need directive
antennas that are able to radiate in any direction across the 360{\deg} azimuth
plane. Conformal antennas that can be simply operated to have multi-functional
performance characteristics are therefore of interest. In this paper, we
present a gradient-index lens antenna designed to radiate with a 45{\deg}
beamwidth across 8 different sectors. When fed by a simple switched feeding
network, the lens is able to provide 360{\deg} azimuth coverage in 45{\deg}
segments. Further analysis of the radiation patterns shows how two distinct
multi-beam patterns can be produced from simple feed networks and simultaneous
excitation of each feeding element. The proposed lens is fabricated by
multi-material 3D printing. The final lens radiates with a gain of 8.5 dBi when
a single sector is excited, and with a maximum gain of 5.9 dBi in multi-beam
mode. Finally, it is shown how the lens can also radiate omnidirectionally when
optimised phase and amplitude weightings are applied to each port.
