Design Optimization of Reconfigurable Liquid Crystal Patch Antenna

Abstract

In various fields such as the 5G antenna system and satellite communication system, there is a growing demand to develop a smart antenna with a frequency selective or beamforming function within a limited space. While antennas utilizing mechanical, electronic, and material characteristics are being studied, a method of having tunable frequency characteristics by applying a liquid crystal material with dielectric anisotropy to a planar patch antenna is proposed. In resonance mode, the design method for using only the minimum amount of expensive liquid crystals is systematically arranged while maximizing the amount of change in the operating frequency of the antenna by considering the electric field distribution on the surface of the patch antenna. Furthermore, to increase the dielectric anisotropy of the liquid crystal, the liquid crystal must be aligned. Simultaneously, in cases where the cell gap of the liquid crystal exceeds 100 μm, the alignment force is weakened. While compensating for this shortcoming, securing the radiation characteristics of the antenna is proposed, and simulations are performed.

Reconfigurable wearable antenna for 5G applications using nematic liquid crystals

“…The threshold voltage required to tilt the LC directors from planar towards the vertical can be determined using [ 25 ] $$$$\begin{equation*} {V}_{c}=\pi \sqrt{\frac{{K}_{11}}{{\varepsilon}_{0}\Delta \varepsilon}}, \end{equation*}$$$$which shows that the cell thickness does not affect the threshold voltage. Although a thick cell will result in a relatively long response time, [ 3 ] thicker LC cells will have a more significant frequency bandwidth variation from switching the director configuration of the LC substrate. In this case, thicker substrates lead to wider antenna tuning frequencies.…”

“…For energy harvesting applications, a tunable frequency bandwidth device enables multiple radio frequency (RF) wavelengths in free space to be harvested. Similarly, for communications applications, a tunable antenna enables wearable devices to transmit and receive broadband information [ 3 ] and helps reduce mismatch and noisy interference when communicating with other devices. [ 4 ] In addition, and in comparison with traditional antennas, a tunable antenna can establish communication with multiple devices with different frequencies, which could play an important role in Multiple In Multiple Out (MIMO) networks, [ 5 ] making dynamically tunable antenna front ends a necessity in the near future.…”

Liquid-crystal-based floating-electrode-free coplanar waveguide phase shifter with an additional liquid-crystal layer for 28-GHz applications

“…Minimization of the thickness of the LC layer is advantageous by increasing the compatibility of the fabrication process with the existing LCD process to enable mass production, and to reduce the dielectric loss and volume of the structure. LC thickness affected a parameter called FoM/LC volume , which should be considered for price competitiveness, as S and T strip varied (figure 7) [28]. At first, FoM/ LC volume decreased rapidly as T LC increased, because the amount of LC between the electrodes was significantly less than the amount in the additional LC layer that has thickness T add.LC .…”

Liquid crystal-based programmable metasurface for terahertz beam manipulation

“…A Design Optimization of Reconfigurable Liquid Crystal Patch Antenna is reported in. 16 A Liquid crystal-based wide-angle metasurface absorber with large frequency tunability and low voltage is published in. 17 In 18 , Reconfigurable liquid crystal reflectarray metasurface for THz communications has been reported.…”