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Simulation results when the LC cell thickness is increased. (a) Mismatch loss (b) insertion loss and (c) phase difference. A relatively constant phase difference can be obtained regardless of the LC cell thickness, but the reflection loss increases as the LC cell thickness becomes thinner.
Source publication
Liquid crystals (LCs) offer a promising playground for developing reconfigurable radio frequency devices due to their unique dielectric properties, including large birefringence and tunability. Previous research on reconfigurable phase shifters has primarily focused on studying loss, response, and tunability. However, the influence of surface-enfor...
Contexts in source publication
Context 1
... performing Electromagnetic simulation (HFSS Ansys Inc), the independent design variable is the cell thickness of the LC. As shown in Fig. 3, the cell thickness of the LC is set to have four different thicknesses from 25 m to 100 m. Note that all parameters of GT7-29007 provided by Merck KGaA are used for the characteristics of the LC in the range of 5 to 8 GHz. The width of the transmission line with 50-ohm impedance is selected based on the LC cell thickness of about ...
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... than -10 dB, whereas as cell thickness is below 50 m, the impedance mismatch losses of the circuit gradually increase; eventually, the circuit with a 25 m cell thickness showed a loss of more than -3 dB. This is reflected in the transmission loss in the same way, and when the cell thickness is reduced to less than 50 m, it can be seen from Fig. 3(b) that the transmission loss due to reflection also increases rapidly. Of course, adding a matching circuit targeting the thin cell cap circuit can reduce return loss. Fig. 3 (c) is the result of predicting the maximum amount of phase shift change that can be obtained according to the cell thickness of the LC. The path along the meander ...
Context 3
... showed a loss of more than -3 dB. This is reflected in the transmission loss in the same way, and when the cell thickness is reduced to less than 50 m, it can be seen from Fig. 3(b) that the transmission loss due to reflection also increases rapidly. Of course, adding a matching circuit targeting the thin cell cap circuit can reduce return loss. Fig. 3 (c) is the result of predicting the maximum amount of phase shift change that can be obtained according to the cell thickness of the LC. The path along the meander line is perpendicular to the cell thickness of the LC, that is, parallel to the substrate above and below the LC. Therefore, the simulation confirmed that the amount of phase ...
Citations
... Several advanced reconfigurable liquid crystal-based devices have been developed, including fast-reconfigurable phase shifters, devices for generating optical vortices, LC-based reconfigurable intelligent surfaces, and liquid crystal gratings. For example, Kim et al. designed a fast-reconfigurable phase shifter utilizing liquid crystal, evaluating its performance for twisted nematic and antiparallel alignment liquid crystal cell configurations 4 . Albero et al. developed two reconfigurable LC devices to generate optical vortices. ...
This study unveils a groundbreaking technique leveraging the superposition of electric field vectors to manipulate liquid crystals (LCs). Demonstrated through a simple configuration of four independent electrodes at the corners of a rectangular enclosure, notably, this configuration can be further simplified or modified as needed, showcasing the versatility of the approach. Significantly, the design showcased in the paper eliminates the need for an alignment layer, highlighting the versatility of the method. Through nuanced adjustments in waveforms, amplitudes, frequencies, and phases in AC or DC from these electrodes, precise control over LC shape deformation and dynamic phase transformation is achieved in both temporal and spatial dimensions. In contrast to traditional methods, the approach presented here abolishes alignment layers and intricate electrode-array systems, opting for a streamlined configuration with varying AC frequencies and DC electric signals. This innovative methodology, founded on simplified governing equations from Q-tensor hydrodynamics theory, demonstrates true 3D control over LCs, displaying efficiency in electrode usage beyond current arrays. The study's contributions extend to temporal control emphasis, superposition techniques, and the elimination of fixed electrodes, promising unprecedented possibilities for programming LC materials and advancing the field of programmable LC devices.
