Compound GRIN Fanbeam Lens Antenna With Wideband Wide-Angle Beam-Scanning

• Published in: IEEE transactions on antennas and propagation Vol. 70; no. 9; pp. 7501 - 7512
• Main Authors: Garcia, Nicolas C., Chisum, Jonathan D.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01-09-2022; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Antenna feeds; Apertures; Array signal processing; Collimation; Compounds; Electromagnetic metamaterials; Extremely high frequencies; gradient index (GRIN) lenses; Lens antennas; Lenses; millimeter wave; Permittivity; Phased arrays; Scanning; Surface morphology; Waveguides
• ISSN: 0018-926X; 1558-2221
• DOI: 10.1109/TAP.2022.3182420

This work presents a parallel-plate waveguide (PPWG) fanbeam antenna achieving a <inline-formula> <tex-math notation="LaTeX">\pm 48^\circ </tex-math></inline-formula> field of view with an average maximum scan loss of <inline-formula> <tex-math notation="LaTeX">2.7\,\textrm {dB} </tex-math></inline-formula> over the Ka-band for a flat feed surface. This approach uses a novel compound gradient index (GRIN) lens system, wherein two GRIN lenses are cascaded axially: an "aperture" lens at the antenna output provides the bulk of the phase collimation, while a "focal" lens near the feed surface corrects the spillover losses and provides additional phase collimation. This arrangement represents a wide-scanning alternative that requires 76% of the axial depth and only 37.3% of the actual material compared to a Luneburg lens fanbeam antenna with similar aperture size. A maximum scan loss of <inline-formula> <tex-math notation="LaTeX">2.58~ </tex-math></inline-formula>dB at 48° and a scan loss exponent of 1.5 are achieved at <inline-formula> <tex-math notation="LaTeX">40~ </tex-math></inline-formula>GHz.