Eight-element liquid crystal based 32 GHz phased array antenna with improved time response

Abstract

Phased array radar systems are used for a wide variety of applications including the precise tracking of airborne craft for air traffic control and providing accurate atmospheric condition information important in weather forecasting. Reducing the cost and size of these radar systems will open new fields to the use of this technology. Using phase control implemented through liquid crystal materials we have created a compact, phased array radar system operating in the microwave range. We report on the construction and testing of a linear, eight element phased array antenna system operating at 32 GHz with element phase controlled by a dual frequency nematic liquid crystal media used as a tunable dielectric. The system was designed using CST Design Studios and Ansys HFSS software. Dual frequency liquid crystals are used to improve beam steering response times. We demonstrate 42 millisecond beam switching times, defined as the time to change the beam focus from one point to another point, controllable beam formation, and beam steering profiles consistent with analytical results and simulation models. The device footprint is a square with sides 9.5 cm long and a thickness less than 2.5 mm. Such a module is easily stackable to create an 8 × 8 phased array system. Our design incorporates a modular construction using PCB for the antennas and input circuitry and a liquid crystal phase control cell with microwave glass substrates. This design simplifies design, construction, and testing as compared to on-glass designs. The device shows an improvement in point-to-point scanning speeds by a factor of 3 as compared to similar liquid crystal based devices and provides continuously variable tuning. Such a device can be used in a system for reduced visibility, directional range finding suitable for automobile collision avoidance systems and rotary wing aircraft landing aids.

Liquid Crystal-Filled 60 GHz Coaxially Structured Phase Shifter Design and Simulation with Enhanced Figure of Merit by Novel Permittivity-Dependent Impedance Matching

“…The nanoscopically molecular orientations of LCs can be macroscopically represented by directors [22,27] that are controllable by these external stimuli (electric, magnetic, temperature, or deformation fields). Fundamentally, their molecular shape anisotropy [24] and the resulting produced variable dipole moments can be exploited to develop a variable dielectric constant (dependent on the interacted field direction) for reconfigurable phase and wavefront steering applications (e.g., tunable filters [28], variable phase shifters [29], tunable antennas [30], and antenna arrays [31]). Arguably, the 5G/6G, IoT, vehicle, and satellite markets are becoming growth engines for the LC mmW industry.…”

Continuously reconfigurable 100 GHz band phased array antenna with improved response time using a microfiber/liquid crystal composite

“…These devices require LC layers ranging from several hundred μm to over 1 mm, resulting in decay times of over 100 s. Many studies have reported PAA using LCs in various frequency bands from microwaves to millimeter waves. [9][10][11][12][13][14][15][16] However, the switching times when configuring the beam pattern are not discussed in most of them. Furthermore, there is no report on PAA that satisfies all three conditions: antenna gain greater than 10 dBi, steering angle greater than 60°, and switching times less than 1 s. Nevertheless, these constitute the fundamental prerequisites for effective operation of PAA devices in practical systems.…”

New quasiperiodic structures in nematic liquid crystals

“…[5][6][7][8][9] Since the discovery of domain walls, topological defects have become a robust field of LC research, with extensive reviews, [10][11][12][13] in addition to the expansive field of LC display applications. [14][15][16][17][18][19][20][21][22][23] Domain walls have been shown to reduce into a pair of disclination lines at a critical field strength, in the pincement process. 24 Newer experiments and theoretical work have reported on velocity of the front to expand the knowledge of this phenomena.…”