Lightweight and Flexible Flat-Knit Metasurfaces, Reflectarrays and Array Antennas

Phased arrays and more generally metasurfaces are a ubiquitous class of optical devices that operate based on the local control of the phase response, and sometimes amplitude response, of individual antenna elements in an overall array ordered such that the collective phase response satisfies some required profile needed to shape an outgoing reflected or transmitted wavefront in a desired manner [1-3]. Lightweight, low-cost phased arrays and metasurfaces that are easily stowable and deployable are desirable for a number of terrestrial and space-based communications and sensing applications [4-5]. Textiles represent an appealing platform for lightweight, low-cost and flexible antennas and considerable research attention in the past few decades has been dedicated towards developing simple fabric-based wearable antennas for communications and on-body sensing applications [6-9]. Considerably less research effort has been dedicated towards fabric-based antenna arrays and more complex types of antennas, such as Yagi-Uda antennas, reflectarrays and other types of functional textile-based devices such as frequency-selective surfaces and integrated waveguides [10-12].<br/><br/>In this work we demonstrate a novel type of lightweight, flexible textile metasurfaces and array antennas made via flat-knitting; these include a metasurface lens, a metasurface vortex beam generator, and a Yagi-Uda antenna. The textile devices were fabricated using a Shima Seiki SRY123LP flat-knitting machine at the Zeis Textile Extension – Knitting Laboratory, NCSU. Two meta-unit archetypes based on different colorwork knitting techniques were used: a simple patch antenna archetype utilizing intarsia colorwork for the Yagi-Uda antenna and a more complex float-jacquard antenna archetype for the metasurface lens and vortex beam generator. Characterization of the device performance in the mm-wave frequency range was carried out at the Advanced Science Research Center, CUNY, and all three devices exhibit desired wavefront shaping capabilities. We compare the tradeoffs between intarsia and float-jacquard flat-knit metasurfaces and compare our flat-knit devices to traditional planar rigid metasurfaces and reflectarrays. Finally, we comment on extensions of this work towards quasi-3D and conformal flat-knit array antennas.<br/><br/>[1] Yu, Nanfang, et al. <i>Sci.</i> 334, 333-337 (2011).<br/>[2] Berry, D., R. Malech, and W. Kennedy.<i> IEEE Trans. Antennas and Propag.</i> 11, 645-651 (1963).<br/>[3] Pozar, David M., Stephen D. Targonski, and H. D. Syrigos. I<i>EEE Trans. Antennas and Propag.</i> 45, 287-296 (1997).<br/>[4] Hodges, Richard E., et al. <i>IEEE Trans. Antennas Propag. Mag. </i>59, 39-49 (2017).<br/>[5] Arya, Manan, et al. <i>AIAA Scitech 2019 Forum</i>. 2019.<br/>[6]Locher, Ivo, et al. <i>IEEE Trans. on Adv. Packag.</i> 29.4 (2006): 777-788.<br/>[7]Klemm, Maciej, and Gerhard Troester. <i>IEEE Trans. on Antennas and Propag.</i> 54.11 (2006): 3192-3197.<br/>[8]Lilja, Juha, et al. " <i>IEEE Trans. on Antennas and Propag.</i> 60.9 (2012): 4130-4140.<br/>[9] Mao, Chun Xu, et al. <i>IEEE Trans. on Antennas and Propag.</i> 68.9 (2020): 6527-6537.<br/>[10] Tahseen, Muhammad M., and Ahmed A. Kishk. IEEE Antennas Propag. Lett. 17, 46-49 (2017).<br/>[11]Alonso-González, Leticia, et al. <i>IEEE Trans. on Antennas and Propag.</i> 66.10 (2018): 5291-5299.<br/>[12]Alonso-González, Leticia, et al. <i>IEEE Trans. on Microw. Theory and Tech.</i> 66.2 (2017): 751-761.