Ellipsoidal Luneburg Lens Binary Array for Wide-Angle Scanning

Abstract

An ellipsoidal Luneburg lens (LBL) binary array is proposed and implemented for wide-angle scanning. In order to solve the occlusion problem between the lens elements in the array, the spherical LBL is transformed into the ellipsoidal LBL based on the transformation optics. The permittivity distribution of the LBL is revised to increase the lens' aperture efficiency when the lens is not particularly large compared with the feed. Further, by introducing the local-beam shifting method, the number of feeds under each lens and the mutual coupling between the feeds can be reduced with the scanning characteristics remained. To validate the proposed design, a 1 × 2 ellipsoidal LBL array has been designed, fabricated, and tested. Each ellipsoidal LBL with 110 mm long-axis radius and 88 mm short-axis radius is fabricated by means of 3-D printing technology. Patch antennas operating at 2.25 GHz are employed as feeds. The measured results show that the proposed ellipsoidal LBL binary array can realize the maximum gain of 15.5 dB at zenith direction and 13.3 dB at 62°. The maximum scanning angle of ±68° can be achieved with a 3 dB gain reduction and -8 dB sidelobe.