Tunable Liquid Crystal Based Phase Shifter with a Slot Unit Cell for Reconfigurable Reflectarrays in F-Band

Abstract

An electrically tuned phase shifter based on the single slot unit cell and liquid crystal for a reconfigurable reflectarray antenna was presented. The simulation and measured results obtained at the F-band were used to demonstrate that the dielectric properties of a nematic state liquid crystal could be exploited to realize a slot unit cell phase shifter for the reconfigurable reflectarrays antennas. By reducing the inhomogeneous of the external electric field in the liquid crystal layer, a lower control voltage and improved model accuracy was obtained. In the experiments test, the achieved saturation bias voltage (10 V) was smaller than the previously reported structure, and the phase shift of the reflectarray greater than 300° was achieved in the frequency range 121.5–126 GHz. The maximum phase shift of 306° occurred at 124.5 GHz.

Programmable Manipulations of Terahertz Beams by Transmissive Digital Coding Metasurfaces Based on Liquid Crystals

“…The effective permittivity of the LCs is set to ε ⊥ = 2.55 and ε // = 3.65, and the loss tangent value is 0.02. [ 37 ]…”

“…[ 32–35 ] To date, LC‐based reflective metasurfaces have been widely demonstrated for phase modulation. [ 36–38 ] Compared with reflective metasurfaces, most LC‐based transmissive metasurfaces do not typically focus on phase modulation. [ 39,40 ] The primary reason for this is the tradeoff between the transmittance and phase tuning range in a non‐magnetic transmissive metasurface.…”

Electronically Tunable Liquid-Crystal-Based F-Band Phase Shifter

“…1(c), are as follows: Px = Py = 1090 µm, Lx1 = Lx2 = 148 µm, Lx3 = 253 µm, Ly1 = 736 µm, Ly2 = 786 µm, Tq = 480 µm, Tp = 60 µm, Ti ≈ 90 nm, and Tc = 500 nm. The LC mixture (HFUT-HB01) is filled inside the device, where the relative permittivity of the two limit states is as follows: ε ⊥ = 2.5, ε // = 3.55, tan(δ ⊥ ) = 0.02, and tan(δ // ) = 0.02 [28].…”

A Novel Electronically Controlled Two-Dimensional Terahertz Beam-Scanning Reflectarray Antenna Based on Liquid Crystals

“…To align the NLCs in a state without bias voltage, two thin aligned polyimide layers were spin-coated on the ground and double-dipole patches. The sandwiched NLCs were LC mixtures (HFUT-HB01) with the following characteristic parameters for the F-band: ε ⊥ = 2.50, ε = 3.69, and tanδ = 0.02 [26]. Assuming that the device is illuminated by a linear polarization and normal incidence plane wave, the electromagnetic performance of the device has been analyzed and optimized using numerical finite element method (FEM) simulation.…”