scholarly journals Electrically Tunable Hydrogen-Bonded Liquid Crystal Phase Control Device

2018 ◽  
Vol 8 (12) ◽  
pp. 2478 ◽  
Author(s):  
Ryota Ito ◽  
Michinori Honma ◽  
Toshiaki Nose
Keyword(s):  
Liquid Crystal ◽  
Phase Shifter ◽  
Continuous Wave ◽  
Phase Control ◽  
Terahertz Wave ◽  
Control Device ◽  
Absorption Properties ◽  
Control Devices ◽  
Wave Control ◽  
Hydrogen Bonded

Terahertz waves have attracted much attention mainly because of their potential in imaging, security checking, nondestructive testing, and information and communication technologies. In the past few years, there has been an extensive effort to investigate terahertz wave control devices. Liquid crystal (LC) devices are strong candidates for high-performance terahertz wave control devices because of their controllability at low drive voltages and their low power consumption. In this study, we fabricated an electrically tunable phase control device by using a hydrogen-bonded LC material. We investigated the performance of the LC phase shifter by using a far infrared continuous wave laser. We also estimated the birefringence and absorption properties of the hydrogen-bonded LC at 2.5 THz by using Jones matrix calculations. The measurements and calculation results indicated that the hydrogen-bonded LC showed no dichroism at 2.5 THz. Based on the absorption properties, we believe that it could be a strong candidate for use in future terahertz devices.

scholarly journals Recent Developments of Reflectarray Antennas for Reconfigurable Beams Using Surface-Mounted RF-MEMS

2012 ◽  
Vol 2012 ◽  
pp. 1-12 ◽  
Author(s):  
Eduardo Carrasco ◽  
Mariano Barba ◽  
Manuel Arrebola ◽  
Jose A. Encinar
Keyword(s):  
Phase Shifter ◽  
Rf Mems ◽  
Low Cost ◽  
Phase Control ◽  
Electronic Control ◽  
Delay Lines ◽  
Mems Switches ◽  
Manufacturing Complexity ◽  
Recent Developments ◽  
Control Devices

Some of the most recent developments in reconfigurable reflectarrays using surface-mounted RF-MEMS, which have been developed at the Universidad Politécnica de Madrid, are summarized in this paper. The results include reconfigurable elements based on patches aperture-coupled to delay lines in two configurations: single elements and gathered elements which form subarrays with common phase control. The former include traditional aperture-coupled elements and a novel wideband reflectarray element which has been designed using two stacked patches. The latter are proposed as a low cost solution for reducing the number of electronic control devices as well as the manufacturing complexity of large reflectarrays. The main advantages and drawbacks of the grouping are evaluated in both pencil and shaped-beam antennas. In all the cases, the effects of the MEMS switches and their assembly circuitry are evaluated when they are used in a 2-bit phase shifter which can be extended to more bits, demonstrating that the proposed elements can be used efficiently in reconfigurable-beam reflectarrays.

Optical phase-control devices using liquid crystal molecular orientation density

2005 ◽  
Author(s):  
Satoshi Yanase ◽  
Marenori Kawamura ◽  
Rumiko Yamaguchi ◽  
Takeshi Takahashi ◽  
Susumu Sato
Keyword(s):  
Liquid Crystal ◽  
Molecular Orientation ◽  
Phase Control ◽  
Optical Phase ◽  
Orientation Density ◽  
Control Devices

scholarly journals Temperature Characterization of Liquid Crystal Dielectric Image Line Phase Shifter for Millimeter-Wave Applications

Crystals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 63
Author(s):  
Henning Tesmer ◽  
Rani Razzouk ◽  
Ersin Polat ◽  
Dongwei Wang ◽  
Rolf Jakoby ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Millimeter Wave ◽  
Insertion Loss ◽  
Phase Shifter ◽  
Ground Plane ◽  
Temperature Dependent ◽  
Differential Phase ◽  
Dependent Behavior ◽  
The Impact ◽  
Temperature Dependent Behavior

In this paper we investigate the temperature dependent behavior of a liquid crystal (LC) loaded tunable dielectric image guide (DIG) phase shifter at millimeter-wave frequencies from 80 GHz to 110 GHz for future high data rate communications. The adhesive, necessary for precise fabrication, is analyzed before temperature dependent behavior of the component is shown, using the nematic LC-mixture GT7-29001. The temperature characterization is conducted by changing the temperature of the LC DIG’s ground plane between −10∘C and 80 ∘C. The orientation of the LC molecules, and therefore the effective macroscopic relative permittivity of the DIG, is changed by inserting the temperature setup in a fixture with rotatable magnets. Temperature independent matching can be observed, while the insertion loss gradually increases with temperature for both highest and lowest permittivity of the LC. At 80 ∘C the insertion loss is up to 1.3dB higher and at −10∘C it is 0.6dB lower than the insertion loss present at 20 ∘C. In addition, the achievable differential phase is reduced with increasing temperature. The impact of molecule alignment to this reduction is shown for the phase shifter and an estimated 85% of the anisotropy is still usable with an LC DIG phase shifter when increasing the temperature from 20 ∘C to 80 ∘C. Higher reduction of differential phase is present at higher frequencies as the electrical length of the phase shifter increases. A maximum difference in differential phase of 72∘ is present at 110 GHz, when increasing the temperature from 20 ∘C to 80 ∘C. Nevertheless, a well predictable, quasi-linear behavior can be observed at the covered temperature range, highlighting the potential of LC-based dielectric components at millimeter wave frequencies.

Space Radiation Environment Testing of Liquid Crystal Phase Shifter Devices

2016 ◽  
Vol 15 ◽  
pp. 1923-1926 ◽  
Author(s):  
Christopher D. Woehrle ◽  
Derek T. Doyle ◽  
Steven A. Lane ◽  
Christos G. Christodoulou
Keyword(s):  
Liquid Crystal ◽  
Phase Shifter ◽  
Space Radiation ◽  
Crystal Phase ◽  
Radiation Environment ◽  
Liquid Crystal Phase ◽  
Space Radiation Environment

scholarly journals Hydrogen-bonded silica gels dispersed in a smectic liquid crystal: A random fieldXYsystem

2002 ◽  
Vol 65 (5) ◽  
Author(s):  
S. Park ◽  
R. L. Leheny ◽  
R. J. Birgeneau ◽  
J.-L. Gallani ◽  
C. W. Garland ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Silica Gels ◽  
Smectic Liquid Crystal ◽  
Hydrogen Bonded

Active Helmholtz Resonator With Positive Real Impedance

2006 ◽  
Vol 129 (1) ◽  
pp. 94-100 ◽  
Author(s):  
Jing Yuan
Keyword(s):  
Noise Control ◽  
Helmholtz Resonator ◽  
Control Device ◽  
Positive Real ◽  
Noise Field ◽  
Strictly Positive Real ◽  
Control Devices ◽  
Passive Noise ◽  
Active Resonator ◽  
Electronic Resonance

The impedance of a passive noise control device is strictly positive real, if the device is installed in noise fields with weak mean flows. Passive noise control devices are, therefore, more reliable than active ones. Active control may be applied to a Helmholtz resonator to introduce electronic resonance. It will affect the impedance Zact of the resonator. A controller may be designed such that (a) Zact is small and resistive at some tunable frequencies; and (b) Re{Zact}⩾0 in the entire frequency range of interest. If criterion (a) is satisfied, the active resonator can suppress duct noise at tunable frequencies. It is difficult to design a controller to satisfy criterion (b) because parameters of the controller depend on acoustic parameters of the noise field. A new method is proposed here to design an active controller to meet both criteria simultaneously. The satisfaction of criterion (b) implies a positive real Zact and a robust active resonator with respect to parameter variation in the noise field. Experimental results are presented to verify the performance of the active resonator.

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