Modeling, Synthesis and Characterization of a Millimeter-Wave Multilayer Microstrip Liquid Crystal Phase Shifter

Abstract

Electromagnetic simulation software is used for modeling the properties of a 2–15 GHz liquid crystal microstrip phase shifter previously designed at Thomson-CSF. After experimental validation of the computed results, the software is applied to the modeling of a new 30–40 GHz multilayer microstrip phase shifter, where the active medium is a liquid crystal inserted between solid dielectric substrates. Measurements carried out at between 10 and 40 GHz on 4.35 cm long lines are in good agreement with theoretical predictions. A maximum experimental phase shift of 219.3° at 37 GHz (about 50°/ cm) was observed for a structure with a commercial liquid crystal (BDH-E44) and silica substrates.

MULTIPLE TIME SCALES OPTICAL NONLINEARITIES OF LIQUID CRYSTALS FOR OPTICAL-TERAHERTZ-MICROWAVE APPLICATIONS (Invited Review)

“…Figures 2(c)-(d), to millimeter-or bulkier microwave devices for tunable -delay line, -phase shifter, -wavelength selector and beam steering devices [26][27][28][29][30][31][32][33][34][35][36][37][38][39][40], to name a few. Nematic liquid crystals are uni-axial, characterized by refractive indices n and the n ⊥ , for light polarization parallel and orthogonal to the director axis, respectively.…”

Microwaves: thin metal slits and liquid crystals

“…Further work has been conducted on millimetre-wave phase shifters using liquid crystal waveguides by Guerin et al (1997) 3 . Tanaka et al (2000) 4 investigated the transmission properties of a grating-patterned electrode structure LC cell.…”

Design of a microwave variable delay line using liquid crystal, and a study of its insertion loss

“…While these dielectric properties are well known for the optical and relatively low-frequency regions, there have been very few studies reporting measurements for the microwave and millimeter-wave regions [10,12]. We therefore measured the dielectric characteristics of a nematic LC (Merck BL-008) which has a large optical refractive index in the microwave band for application to microwave devices.…”

“…Lims group reported a voltage-controlled millimeter-wave variable phase shifter implemented by filling a waveguide with nematic LC [10]. Dolfis group reported a wide-range microwave and millimeter-wave variable phase shifter that employs nematic LC as the dielectric of microstrip lines [11,12]. However, we can guess from the measured dielectric characteristics of LC materials [1013], that the insertion loss of LC microwave devices is too large for practical use.…”