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).
We propose an F-band phase shifter based on the nematic liquid crystals (NLCs). The proposed phase shifter is formed by a voltage-controlled cavity through introducing an NLC layer between a dipole structure array and a metal floor. Under the action of electric field, the orientation of the NLC molecules will be deflected. We adjust the resonant frequency and phase of the reflected electromagnetic (EM) wave by tuning the permittivity. The transmission characteristics and the LC parameters are calculated and analyzed for EM waves within the frequency range from 85 to 115 GHz. The LC-based device with a 30 × 30 array of two parallel unequal dipoles is printed on a quartz substrate, with 4 cm × 4 cm area and 490 µm thickness. The experimental results show that phase shift of zero to 350.7 • is achieved at 104.2 GHz by changing the applied bias voltage on the LC layer from 0 to 20 V. Considering the anisotropy and inhomogeneity of the LC, an improved electrification model is established and compared with the test results. The proposed phase shifter is expected to find several applications in millimeter wave and terahertz reconfigurable antenna systems.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.