77‐1: <i>Invited Paper:</i> Liquid Crystals beyond Displays: Smart Antennas and Digital Optics

Fritzsch, Carsten; Snow, B.D.; Sargent, Joe; Klass, Dagmar; Kaur, S.; Parri, Owain

doi:10.1002/sdtp.13120

Cited by 16 publications

(11 citation statements)

References 8 publications

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“…With the emergence and progress of newly developed LC mixtures specifically synthesized for microwaves since 2002 [45][46][47][48][49][50][51][52][53][54][55][56][57][58][59][60], innovative concepts and designs with appropriate biasing schemes enabled numerous high-performance MLC components and devices in the RF domain, which fully exploit the microwave LC´s unique properties: various planar delay line, metallic and dielectric . Scenario of various applications and platforms with some important characteristics, including beam-steering antennas and agile components, following the software-controlled radio approach.…”

Section: Introductionmentioning

confidence: 99%

“…With the emergence and progress of newly developed LC mixtures specifically synthesized for microwaves since 2002 [45][46][47][48][49][50][51][52][53][54][55][56][57][58][59][60], innovative concepts and designs with appropriate biasing schemes enabled numerous high-performance MLC components and devices in the RF domain, which fully exploit the microwave LC's unique properties: various planar delay line, metallic and dielectric waveguide phase shifters at different frequencies [45][46][47], tunable resonators and filters [85][86][87][88][89][90][91][92][93][94][95][96][97][98][99], tunable power dividers and RF switches [80,[99][100][101][102][103][104], tunable metamaterial structures, frequency-selective and high-impedance surfaces [105][106][107][108][...…”

Section: Introductionmentioning

confidence: 99%

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

Jakoby

Gaebler²,

Weickhmann³

2020

Crystals

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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.

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Section: Introductionmentioning

confidence: 99%

“…With the emergence and progress of newly developed LC mixtures specifically synthesized for microwaves since 2002 [45][46][47][48][49][50][51][52][53][54][55][56][57][58][59][60], innovative concepts and designs with appropriate biasing schemes enabled numerous high-performance MLC components and devices in the RF domain, which fully exploit the microwave LC's unique properties: various planar delay line, metallic and dielectric waveguide phase shifters at different frequencies [45][46][47], tunable resonators and filters [85][86][87][88][89][90][91][92][93][94][95][96][97][98][99], tunable power dividers and RF switches [80,[99][100][101][102][103][104], tunable metamaterial structures, frequency-selective and high-impedance surfaces [105][106][107][108][...…”

Section: Introductionmentioning

confidence: 99%

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

Jakoby

Gaebler²,

Weickhmann³

2020

Crystals

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“…The multiplication with ϵ s in (5) can be viewed as scaling of the overall capacitance of the structure in Figure 9. The capacitance of the air-filled TL is needed to evaluate ϵ eff of an anisotropic TL in (5). For a given ratio W/H the parameter m of elliptic integrals can be found from ( 21), (22) and C air from (20).…”

Section: Aramaismentioning

confidence: 99%

“…2,4 The additional momentum for technological advancements of the microwave LC technology was given by recent progress in synthesis of LCs with increased birefringence, shorter switching time and operation frequencies extending to the THz range. [5][6][7] One of the key components of LC-based reconfigurable antenna systems is a phase shifter (PS), 1,2,[6][7][8][9] a guided wave structure that exploits electronically controllable anisotropy of LC to modify the output phase for beamforming in antenna arrays. Depending on the application, a variety of guided wave structures can be used that include transmission lines (TLs) of various topology as well as metallic or dielectric waveguides filled with LC.…”

Section: Introductionmentioning

confidence: 99%

Design formulas for liquid crystal phase shifter based on microstrip transmission line

Kobyakov

Zakharian

2021

Int J RF Microw Comput Aided Eng

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Closed-form analytical formulas are presented to calculate a figure of merit (FoM) of a liquid crystal (LC) phase shifter (PS) based on microstrip transmission line (MS TL). New expressions are derived to account for anisotropic loss of LC and loss in the superstrate. Although approximate, the presented framework provides a useful insight into the effect of numerous design parameters of the LC PS, such as geometric dimensions of TL or complex permittivity of LC and the superstrate. Comparison with the full-wave numerical analysis of Maxwell's equations showed good agreement in the calculated effective permittivity, dielectric and conductor losses and the FoM for operating frequencies up to 12 to 15 GHz. Furthermore, reasonable quantitative agreement for the FoM is maintained for geometries of interest even at millimeter wave frequencies, up to 30 GHz.

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“…The phased array antenna is promising as a directional antenna, due to its beamforming functionality. Figure 1 shows a schematic diagram of the phased array antenna 3,4) . We have been researching on evaluation of highfrequency dielectric behaviors in LC materials 11) .…”

Section: Introductionmentioning

confidence: 99%

[Paper] Systematic Investigation of Molecular Structure of Nematic-phase Liquid Crystals for Reduction of Dielectric Loss in Microwave Control Applications

Murakami

Shibata

Sato

et al. 2020

MTA

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For realization of phase shifting using a liquid crystal (LC) that can continuously control the phase of microwaves, we evaluated the relationship between the molecular structure of the LC, which assumes a nematic phase at room temperature, and the dielectric loss in microwave frequency. The results indicated that the LC has a rigid molecular structure, has fluorine as a polar group, and is in a low temperature, leading to lower dielectric loss. From these results, we considered that dielectric loss can be reduced by suppression of the thermal vibration of LC molecules under microwave exposure.

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77‐1: Invited Paper: Liquid Crystals beyond Displays: Smart Antennas and Digital Optics

Cited by 16 publications

References 8 publications

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

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

Design formulas for liquid crystal phase shifter based on microstrip transmission line

[Paper] Systematic Investigation of Molecular Structure of Nematic-phase Liquid Crystals for Reduction of Dielectric Loss in Microwave Control Applications

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