Near-Field Angular Scan Enhancement of Antenna Arrays Using Metasurfaces

• Published in: IEEE transactions on antennas and propagation Vol. 71; no. 3; pp. 2350 - 2362
• Main Authors: Egorov, Gleb A., Eleftheriades, George V.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.03.2023; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Antenna arrays; Beam steering; Degradation; Directivity; Far fields; Gratings; Lenses; Mathematical analysis; Metasurfaces; Near fields; Optics; Phased arrays
• ISSN: 0018-926X; 1558-2221
• DOI: 10.1109/TAP.2022.3164137

In this publication, we continue our previous work on extending the angular scan range of phased arrays using metasurfaces. We consider in detail scan enhancement using a single metasurface lens in the near-field of a source and provide analytical expressions for source excitation to obtain a desired beam. We show that such a device suffers from the same directivity degradation as in the case of far-field lens placement. Moreover, we discuss in detail that this approach has limitations, and one cannot place the lens arbitrarily close to the source array. We then propose a two-lens near-field scan enhancer which is not subject to the same limitations, although still subject to the same directivity degradation. Finally, we propose a binary metasurface concept which theoretically achieves desired scan enhancement without directivity degradation. Some theoretical claims are then verified via full-field simulations.