scholarly journals Microwave Liquid Crystal Enabling Technology for Electronically Steerable Antennas in SATCOM and 5G Millimeter-Wave Systems

Crystals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 514 ◽  
Author(s):  
Rolf Jakoby ◽  
Alexander Gaebler ◽  
Christian Weickhmann
Keyword(s):  
Liquid Crystal ◽  
Phase Shift ◽  
Millimeter Wave ◽  
Phase Shifter ◽  
Beam Steering ◽  
Phase Shifters ◽  
Worst Case ◽  
Differential Phase Shift ◽  
Digital Architecture ◽  
Differential Phase

Future satellite platforms and 5G millimeter wave systems require Electronically Steerable Antennas (ESAs), which can be enabled by Microwave Liquid Crystal (MLC) technology. This paper reviews some fundamentals and the progress of microwave LCs concerning its performance metric, and it also reviews the MLC technology to deploy phase shifters in different topologies, starting from well-known toward innovative concepts with the newest results. Two of these phase shifter topologies are dedicated for implementation in array antennas: (1) wideband, high-performance metallic waveguide phase shifters to plug into a waveguide horn array for a relay satellite in geostationary orbit to track low Earth orbit satellites with maximum phase change rates of 5.1°/s to 45.4°/s, depending on the applied voltages, and (2) low-profile planar delay-line phase shifter stacks with very thin integrated MLC varactors for fast tuning, which are assembled into a multi-stack, flat-panel, beam-steering phased array, being able to scan the beam from −60° to +60° in about 10 ms. The loaded-line phase shifters have an insertion loss of about 3 dB at 30 GHz for a 400° differential phase shift and a figure-of-merit (FoM) > 120°/dB over a bandwidth of about 2.5 GHz. The critical switch-off response time to change the orientation of the microwave LCs from parallel to perpendicular with respect to the RF field (worst case), which corresponds to the time for 90 to 10% decay in the differential phase shift, is in the range of 30 ms for a LC layer height of about 4 µm. These MLC phase shifter stacks are fabricated in a standard Liquid Crystal Display (LCD) process for manufacturing low-cost large-scale ESAs, featuring single- and multiple-beam steering with very low power consumption, high linearity, and high power-handling capability. With a modular concept and hybrid analog/digital architecture, these smart antennas are flexible in size to meet the specific requirements for operating in satellite ground and user terminals, but also in 5G mm-wave systems.

Reliability study of a tunable Ka-band SIW-phase shifter based on liquid crystal in LTCC-technology

2014 ◽  
Vol 7 (5) ◽  
pp. 521-527 ◽  
Author(s):  
Sebastian Strunck ◽  
Alexander Gaebler ◽  
Onur H. Karabey ◽  
Andreas Heunisch ◽  
Baerbel Schulz ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Phase Shifter ◽  
Effective Permittivity ◽  
Phase Shifters ◽  
Phased Array Antenna ◽  
Differential Phase Shift ◽  
Differential Phase ◽  
Phase Errors ◽  
Antenna Module ◽  
High Level

A tunable substrate-integrated waveguide phase shifter using low-temperature co-fired ceramic (LTCC)-technology is presented in this paper. By changing the effective permittivity in the liquid crystal (LC)-filled waveguide, the differential phase can be tuned continuously. This is achieved by means of an analog signal applied to the electrodes, surrounding the LC. The design allows for precise tuning of the differential phase, which is proven with a Monte Carlo measurement resulting in phase errors of less than 3° at 28 GHz. Besides that, the ambient temperature dependency of the module is shown. The phase shifter has a high integration level and can be included into a complete and lightweight single-phased array antenna module. The phase shifter is realized with a high level of integration which is available through the multilayer process of the LTCC. It has a length of 50 and provides a differential phase shift of more than 360° at 28 GHz. The figure of merit for tunable phase shifters is >40°/dB.

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.

scholarly journals Microwave Liquid Crystal Technology

Crystals ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 355 ◽  
Author(s):  
Holger Maune ◽  
Matthias Jost ◽  
Roland Reese ◽  
Ersin Polat ◽  
Matthias Nickel ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Millimeter Wave ◽  
Antenna Arrays ◽  
High Performance ◽  
Beam Steering ◽  
Phase Shifters ◽  
Dielectric Waveguides ◽  
Microwave Components ◽  
Recent Developments ◽  
Rectangular Waveguides

Tunable Liquid Crystal (LC)-based microwave components are of increasing interest in academia and industry. Based on these components, numerous applications can be targeted such as tunable microwave filters and beam-steering antenna systems. With the commercialization of first LC-steered antennas for Ku-band e.g., by Kymeta and Alcan Systems, LC-based microwave components left early research stages behind. With the introduction of terrestrial 5G communications systems, moving to millimeter-wave communication, these systems can benefit from the unique properties of LC in terms of material quality. In this paper, we show recent developments in millimeter wave phase shifters for antenna arrays. The limits of classical high-performance metallic rectangular waveguides are clearly identified. A new implementation with dielectric waveguides is presented and compared to classic approaches.

scholarly journals Acoustic Wave Reflection Control Based on Broadband Differential Phase Shifters

2021 ◽  
Vol 7 ◽  
Author(s):  
Zifu Qin ◽  
Xiaohan Liu ◽  
Chu Ma
Keyword(s):  
Phase Shift ◽  
Acoustic Waves ◽  
Phase Shifter ◽  
Wave Reflection ◽  
Phase Shifters ◽  
Complex Phase ◽  
Reflected Waves ◽  
Differential Phase ◽  
Location Patterns ◽  
Working Frequency

Controlling the flow of acoustic waves has broad applications in acoustic imaging, communication, energy harvesting, audio systems, etc. Metasurfaces have been developed for wave control. In this work we propose the design of broadband differential phase shifters for acoustic reflected waves, which can achieve nearly constant phase shift values over a broad frequency ranges. We further demonstrate the design of a broadband differential π phase shifter that works in the frequency range of (10 kHz, 16 KHz) and its applications in acoustic metasurfaces for steering and focusing of reflected acoustic waves. The metasurfaces we designed have the following advantages: 1) The metasurface is formed with binary patterns instead of more complex phase discretization steps, thus the metasurface realization is less complex for fabrication and assembly. 2) The phase shift values of the two basic phase shifter elements are broadband, thus we do not need to fabricate new elements for each frequency. Rearranging the same elements into different location patterns would allow us to tune the working frequency of the metasurfaces.

scholarly journals Potential of Liquid-Crystal Materials for Millimeter-Wave Application

2018 ◽  
Vol 8 (12) ◽  
pp. 2544 ◽  
Author(s):  
Toshiaki Nose ◽  
Ryota Ito ◽  
Michinori Honma
Keyword(s):  
Liquid Crystal ◽  
Millimeter Wave ◽  
Microstrip Line ◽  
Phase Shifter ◽  
Substrate Surface ◽  
Antenna System ◽  
Phase Shifters ◽  
Phased Array Antenna ◽  
Electric Circuits ◽  
Line Type

In this study, we reviewed three topics regarding the application of liquid-crystal (LC) materials to millimeter-wave (MMW) devices. It is essential to develop useful measurement methods for refractive indices of LC materials in the MMW region. Herein, a novel measurement method using optical short is demonstrated using a Si semiconductor substrate. There are two approaches to develop MMW LC devices. One is the quasi-optical approach, which involves scaling up the optical components, and the other approach involves integrating the LC materials into high-frequency electric circuits. A three-dimensional (3D) printer is used to fabricate the Fresnel lens, which is a typical quasi-optical device useful in the MMW region, where we can develop the tunable lens by introducing LC materials. A planar-type MMW waveguide is advantageous for integrating the LC materials to develop LC MMW devices using the second approach. We investigated a useful microstrip-line-type LC phase shifter by developing a novel conversion circuit to introduce the LC material onto the dielectric substrate surface. A phase shifter is an important MMW component that is used to attain a phased array antenna system, and a minimal twin antenna array is demonstrated using the microstrip-line-type LC phase shifters.

scholarly journals Reconfigurable Millimeter-Wave Components Based on Liquid Crystal Technology for Smart Applications

Crystals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 346 ◽  
Author(s):  
Ersin Polat ◽  
Henning Tesmer ◽  
Roland Reese ◽  
Matthias Nickel ◽  
Dongwei Wang ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Millimeter Wave ◽  
Beam Steering ◽  
Phase Shifters ◽  
Dielectric Waveguides ◽  
Promising Alternative ◽  
Single Antenna ◽  
W Band ◽  
Antenna Type ◽  
High Degree

This paper presents recent development of tunable microwave liquid crystal (LC) components in the lower millimeter wave (mmW) regime up to the W-band. With the utilization of increasing frequency, conventional metallic waveguide structures prove to be impractical for LC-based components. In particular, the integration of the electric bias network is extremely challenging. Therefore, dielectric waveguides are a promising alternative to conventional waveguides, since electrodes can be easily integrated in the open structure of dielectric waveguides. The numerous subcategories of dielectric waveguides offer a high degree of freedom in designing smart millimeter wave components such as tunable phase shifters, filters and steerable antennas. Recent research resulted in many different realizations, which are analyzed in this paper. The first demonstrators of phased array antennas with integrated LC-based phase shifters are reviewed and compared. In addition, beam steering with a single antenna type is shown. Furthermore, the possibility to realize tunable filters using LC-filled dielectric waveguides is demonstrated.

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