김호겸 교수

This communication presents a novel systematic design of a high-aperture-efficiency and 2-D beam-scanning nematic liquid-crystal (LC)-based reflectarray (LCRA) that operates in the sixth-generation (6G) midband (7–24 GHz). Despite a 260° phase range, the maximum aperture efficiency is 35.8% at an aperture dimension (F/D) ratio of 0.58, the highest aperture efficiency at the lowest F/D ratio among LCRAs designed to operate on the mmWave band. The proposed LC-based reflectarray unit cell (LC-RUC)

This study presents a new class of independently polarization manipulable liquid-crystal (LC)-based reflective metasurface (RMS) antenna. To the best of the authors’ knowledge, this study first introduces independent polarization controllability of the LC-based RMS in mmWave. Two LC layers are embedded into the proposed structure for independent manipulation of the polarization. Isolation topologies, such as rectangular patch shape and metal strip ground, are used to enhance polarization purity,

This letter presents a novel design of a nematic liquid-crystal (LC)-based <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">X</i> -band reactively loaded reflectarray unit cell (RLRUC) to reduce reflection loss. The reflection loss of an LC-based reflectarray unit cell (RUC) can be reduced by increasing the thickness of the LC or the superstrate. However, in the conventional RUC, the superstrate thickness has little impact on the reflection loss d

This letter proposes a low-voltage controlled fast beam switchable liquid-crystal-based reflectarray (LC-RA). By introducing a strip array of ground patterns and a transverse rubbing layer, a 1.5 V-powered falling response can be achieved for fast beam switching. Typically, the falling response of the LC cannot be controlled by the bias voltage, leading to slow beam switching. The strip array, in conjunction with the top electrodes, generates lateral fields for arranging the molecules of the LC,

In this article, closed-form characterization of anisotropic polymer network liquid-crystal (PNLC) for reconfigurable RF devices at the millimeter-wave (mmWave) band is achieved. For the first time, the complex permittivity of the PNLC has been extracted for various doping conditions of reactive mesogen used in the polymer network at the mmWave band. Anisotropic constitutive parameters at the two extreme states of the PNLC can be obtained through a waveguide (WG). A 1 × 2 reflectarray simple cel

The fabrication and design of a liquid crystal (LC)-based X-band reflectarray antenna are described. A high-efficiency reflectarray antenna was achieved by defining and optimizing its efficiency parameters. Considering the high loss tangent of the LC, the equivalent circuit of the lossy medium was modeled, and the reflection loss of the unit cell was minimized. Furthermore, a 2×2 patch array antenna was employed to optimize the spillover and taper efficiency. To minimize blockage loss, the refle

This paper presents a novel dual-linearly polarized liquid crystal reflectarray antenna (DLP-LCRA) based on a printed circuit board (PCB) process. The proposed design employs a bridge-shaped biasing topology to reduce RF losses typically associated with bias lines in PCB-based implementations. While conventional DLP-LCRAs are often fabricated using glass substrates due to the difficulty of achieving sufficiently thin bias lines in PCB processes, this work demonstrates that a cost-effective and p

This article presents a low-power consumption and beam-holding reconfigurable intelligent surface (RIS) for reliable millimeter-wave 5G fixed wireless communication. Conventional RIS designs require continuous power to maintain beamforming, with power consumption divided into two main parts: power drawn by the control board and power dissipated by unit cells. The strategies for reducing power consumption differ based on the adjustable components used. In this study, a liquid crystal (LC)-based R

We present a low-power-consumption and beam-sustainable reconfigurable intelligent surface (RIS) for reliable millimeter-wave 5G fixed wireless communication in non-line-of-sight (NLOS) scenarios. Conventional RIS designs require continuous power to maintain beamforming, with power consumption divided into two main parts: power drawn by the control board and power dissipated by unit cells. The strategies for reducing power consumption differ based on the adjustable components used. In this study

We present a 2-bit reconfigurable intelligent surface (RIS) designed for operation in the 6 G upper-mid band, enabling integrated sensing and communication (ISAC). The proposed RIS achieves indepdent polarization controllability, which can be utilized for both communication and sensing concepts, the proposed RIS structure is employed alongside customized ray-tracing, which is not supported by commercial tools. This approach enables the sensing and positioning of targets, as well as the demonstra