Reconfigurable Millimeter-Wave Reflectarray Based on Low-Loss Liquid Crystals

Abstract

This article reports on the development and evaluation of a reconfigurable millimeter-wave reflectarray (RA) based on liquid-crystal (LC) substrate operating in the D-band (105–125 GHz). The RA is composed of a high-impedance surface (HIS) with a meta-array of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$33\times 29$ </tex-math></inline-formula> patches on a 2-mm-thick quartz substrate, separated from the ground plane (GP) by a 40- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> -thick LC layer. A novel LC composition with low dielectric losses (< 0.003) and high dielectric anisotropy ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$&gt;$ </tex-math></inline-formula> 1.3) has been developed for operation at millimeter waves. The results demonstrate a reflection phase tunability of 210° and low insertion losses of 2.5 dB. Furthermore, the device was demonstrated as a proof of concept for 1-D beam-steering applications, exhibiting an operational bandwidth of 12 GHz.