Electronically Tunable Liquid-Crystal-Based F-Band Phase Shifter

Abstract

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.

A Dual-Polarized Reconfigurable Reflectarray With a Thin Liquid Crystal Layer and 2-D Beam Scanning

“…A major step in the LC RA design is to obtain the relations between reflection phase and applied bias voltage. To obtain this relation, a free space measurement [7] should be carried out with one horn for illuminating and the other one for receiving. Several fixtures are manufactured with a 3D printer that holds two horns above the RA surface with different heights and incident angles.…”

“…LC-based RAs use LC as the tuning substrate material that can change the reflective phase of the unit cell in the presence of applied voltage. Numerous studies have been carried out for LC-based unit cells with basic structures like square patches [4]- [6], multiple dipoles [7]- [9], and rectangular slots [10]. In addition, some other techniques were also exploited for LC-based unit cells [11] [12].…”

Development of Beam Steerable Reflectarray With Liquid Crystal for Both E-Plane and H-Plane

“…Contrarily, LC is low cost and easily integrated to antennas and microwave devices with planar structures, which is suitable to be assemble to the RA. As a result, studies of LC applications on RA technology at millimeter wave have increased a lot [26]- [30].…”

“…The LC RA usually uses the material properties that can change relative permittivity by adding quasi-static electric field to the electrodes [22], [35]. When different voltages are applied to the Patch layer of RA relative to the ground, phase with different values of reflected wave from the RA is achieved.…”