Employing Liquid Crystal‐Based Smart Antennas for Satellite and Terrestrial Communication

Wittek, Michael; Fritzsch, Carsten; Schroth, Dieter

doi:10.1002/msid.1178

Cited by 14 publications

(12 citation statements)

References 11 publications

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“…It is advisable to keep an eye not only on the generic modalities of phase shift and insertion loss, but also on integrating more specific variables underlying the device operation, e.g., driving voltage, power handling, volume, weight, viscosity, temperature dependence, fabrication cost, and the stability of insertion loss magnitude over different driving voltages, among others. A more comprehensive performance metric can arguably enhance decision-making in navigating LCs for bespoke mmWave applications (e.g., inter-satellite links [31] and satellite internet [32]) beyond the photonics-based display sector. Though the results from this work are exclusively dedicated to LC SCPW phase shifters at 60 GHz, the implications are to a great extent transferrable to the performance evaluation of other LC-based reconfigurable mmWave devices, such as resonators, filters, etc.…”

Section: Discussionmentioning

confidence: 99%

Rethinking Figure-of-Merits of Liquid Crystals Shielded Coplanar Waveguide Phase Shifters at 60 GHz

2021

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The demand for reconfigurable millimetre-wave (mm-Wave) components based on highly anisotropic liquid crystals (LC) is higher than ever before for the UK and worldwide. In this work, 60 GHz investigation on a bespoke shielded coplanar waveguide (SCPW) phase shifter structure filled with 16 types of microwave-enabled nematic LCs respectively indicates that the patterns of the device’s figure-of-merit (FoM, defined as the ratio of maximum differential phase shift to maximum insertion loss) reshuffle from those of the characterised LC materials’ FoM (defined as the ratio of tunability to maximum dissipation factor). To be more specific, GT7-29001- and MDA-03-2838-based phase shifters exhibit the highest FoM for devices, outperforming phase shifters based on GT5-28004 and TUD-566 with the highest FoM for materials. Such a mismatch between the device’s FoM and LC’s FoM implies a nonlinearly perturbed wave-occupied volume ratio effect. Furthermore, the relationship between insertion loss and the effective delay line length is nonlinear, as evidenced by measurement results of two phase shifters (0–π and 0–2π, respectively). Such nonlinearities complicate the established FoM metrics and potentially lead to a renewed interest in the selection and material synthesis of LCs to optimise reconfigurable mmWave devices, and promote their technological exploitation in phased array systems targeting demanding applications such as inter-satellite links and satellite internet.

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Section: Discussionmentioning

confidence: 99%

Rethinking Figure-of-Merits of Liquid Crystals Shielded Coplanar Waveguide Phase Shifters at 60 GHz

2021

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“…In this work, the LC mixture licriOn TM GT7-29001 from Merck KGaA is used, which is specifically optimized and synthesized for microwave applications. Its permittivity ranges from ε r, = 3.53 to ε r,⊥ = 2.46 with a dissipation factor between tan δ = 0.0064 and tan δ ⊥ = 0.0116 at 19 GHz [36].…”

Section: Microwave Liquid Crystal Technologymentioning

confidence: 99%

Bandwidth and Center Frequency Reconfigurable Waveguide Filter Based on Liquid Crystal Technology

Kamrath¹,

Polat²,

Matic³

et al. 2022

IEEE J. Microw.

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This paper presents for the first time a fully electronically reconfigurable waveguide filter tunable in bandwidth and center frequency based on liquid crystal (LC) technology. A continuously reconfigurable two pole bandpass filter is designed and characterized in the Ka-band at 30 GHz. To be able to tune both center frequency and bandwidth independently, the resonators and coupling structures are filled with LC as tunable material. Hence, the filter's center frequency and coupling strengths can be tuned and, furthermore, tuning with constant filter characteristic is possible. To tune the LC, a novel two-layer electrode design for waveguide structures is presented, which is simple to integrate and provides a high tuning efficiency with low insertion loss. By applying different bias configurations, the LC's effective permittivity can be varied, and therefore, also the resonators' electrical lengths. The presented two pole filter can adapt its center frequency from 29.8 GHz to 30.7 GHz with a maximum 3 dB bandwidth variation from 660 MHz to 870 MHz. The measurements are carried out with bias voltages up to ±250 V.INDEX TERMS Microwave filter, liquid crystals, millimeter wave communication, tunable circuits and devices, K-band.This article has been accepted for inclusion in a future issue of this journal. Content is final as presented, with the exception of pagination.

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“…Their final dimensions are optimized with CST Studio Suite. The LC mixture used in this work is GT7-29001 from Merck KGaA, Darmstadt, Germany with following parameters given at 19 GHz: ε r,|| = 3.53, ε r,⊥ = 2.46, tan δ || = 0.0064 and tan δ ⊥ = 0.0116 [39]. Therefore, the dielectric anisotropy of the material is ε r = ε r,|| − ε r,⊥ = 1.07.…”

Section: Unit Cell and Antenna Designmentioning

confidence: 99%

Reconfigurable Liquid Crystal Dielectric Image Line Leaky Wave Antenna at W-Band

et al. 2022

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This paper presents a reconfigurable dielectric image line leaky wave antenna at W-band. Reconfigurability is achieved by applying bias to anisotropic liquid crystal (LC) filled into the antenna. Instead of separating RF components and DC-bias network by complex or space consuming methods, the bias electrodes are simultaneously used as radiation elements. In order to evaluate this concept, a non-reconfigurable antenna with isolated unit cells is compared to a reconfigurable antenna, which has its unit cells connected by a metallic line. The non-reconfigurable demonstrator shows gain of up to 18 dBi and can scan through broadside from −30 • to +10 • in the investigated frequency range from 75 GHz to 102 GHz. This frequency scanning sector can be shifted by 10 • when utilizing the reconfigurable LC antenna, while gain of up to 15 dBi is maintained. Since the bias electrodes are directly mounted on the image line, less than 50 V is necessary to control the LC. The antenna is comparably easy to fabricate, and only one bias voltage is directly related to a steering angle, which can be advantageous compared to complex phased arrays with multiple LC phase shifters.INDEX TERMS Beam steering, dielectric image line, leaky wave antennas, liquid crystal, W-band.

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Employing Liquid Crystal‐Based Smart Antennas for Satellite and Terrestrial Communication

Cited by 14 publications

References 11 publications

Rethinking Figure-of-Merits of Liquid Crystals Shielded Coplanar Waveguide Phase Shifters at 60 GHz

Rethinking Figure-of-Merits of Liquid Crystals Shielded Coplanar Waveguide Phase Shifters at 60 GHz

Bandwidth and Center Frequency Reconfigurable Waveguide Filter Based on Liquid Crystal Technology

Reconfigurable Liquid Crystal Dielectric Image Line Leaky Wave Antenna at W-Band

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