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.

This paper introduces a tunable metamaterial absorber (MA) based on polymer network liquid crystal (PNLC) in the terahertz (THz) frequency band. Under the optimal polymerization condition, through electrical control of the orientation of the PNLC embedded in the frequency selective surface, the resonant frequency of the absorber can be tuned from 416.5 to 405.0 GHz, corresponding to fractional frequency bandwidth of 2.8%. The experimental results show that the proposed MA based on the PNLC offers an adjustment time of 10 ms and recovery time of 85 ms, which is significantly faster than the tunable metamaterial devices based on conventional nematic liquid crystal (LC).

In the previous work, two new nematic liquid crystal (NLC) mixtures, E7-2 and S200-2, were produced by adding eight LC monomers to two commercial LCs S200 and E7, respectively. At λ = 589 nm, the birefringence (Δn) characteristics of the two LC nematic mixtures E7-2 (Δn = 0.260) and S200-2 (Δn = 0.298) are greater than those of the commercial LC E7 (Δn = 0.224) and S200 (Δn = 0.266). The properties (T_N-I, ε_//, Δɛ, K₁₁, and K₃₃) of these four NLCs were measured. A double-layer metal loop arrays modulation structure based on metamaterial (MM) metal–dielectric–metal (MDM) was designed and fabricated for use in the THz frequency range. The results show that the LC mixtures E7-2 and S200-2 have greater modulation depth (MD) and less modulation insertion loss (IL) than E7 and S200 at THz frequencies. The results show that LC mixtures have significant potential for designing active tunable LC-based devices in the THz and visible light range.

We present a wideband metamaterial (MM) filter based on a metal-dielectric-metal (MDM) structure. The proposed structure consists of a quartz dielectric substrate and two metallic square-loop arrays, which were deposited on both surfaces of the substrate. The performance of the proposed design was numerically simulated by considering the angle of incidence. The surface current and electric field distributions were calculated for the two resonant frequencies to examine the intrinsic mechanism of the proposed filter. The transmittance of the structure for various oblique angles of incidence was also analyzed. It is generally challenging to completely align the two metallic layers due to limitations in the manufacturing process. Hence, the influence of periodic misalignment on wave propagation was studied. Furthermore, a prototype of the proposed structure was fabricated and the transmission spectra were measured. Simulation and experimental results reveal that our proposed filter can achieve wideband transmission in the F-band. This work is valuable for the design of broadband filters in millimeter and terahertz waves.