A Novel E-plane-Focused Cylindrical Luneburg Lens Loaded with Metal Grids for Sidelobe Level Reduction

A novel cylindrical Luneburg lens operating at 26 GHz-band using hole drilling technology are reported, aiming at proper radiation patterns. The cylindrical Luneburg lens antenna converge microwaves in the plane perpendicular to the generatrix of the cylinder. An E-plane-focused cylindrical Luneburg lens antenna with the thickness of 20 mm and diameter of 88.2 mm is proposed for working at 26 GHz. Feed of the lens antenna is a conventional rectangular waveguide. Furthermore, in order to compensate the phase of the microwave in the nonconverging plane (H-plane in this case), a pair of printed circuit boards (PCBs) etched with particular metal grids is attached to the side faces of the lens. With optimized design for the grids, a narrower beam is obtained in the H-plane while the sidelobe level (SLL) of the cylindrical Luneburg lens could be drastically reduced compared with lens antenna without the special metal grids. Measured results of the fabricated lens antennas are in a good agreement with the simulation, proving its effectiveness and practicability that the designed grids benefit the radiation pattern performances. With an appropriate pattern for the H-plane achieved, proposed cylindrical Luneburg lens operating at millimeter-wave (mmW) band is a suitable candidate for multibeam communication systems.