Tunable Liquid Crystal Filter in Nonradiative Dielectric Waveguide Technology at 60 GHz

Polat, Ersin; Reese, Roland; Jost, Matthias; Schuster, Christian; Nickel, Matthias; Jakoby, Rolf; Maune, Holger

doi:10.1109/lmwc.2018.2884152

Cited by 38 publications

(25 citation statements)

References 6 publications

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“…Additionally, LCs need an especially low bias voltage compared to other tunable materials like ferrites or other devices like MEMS. For these reasons, the development of reconfigurable LC-based devices for MW or mmW applications has gotten the attention of the research community in recent years, and several reconfigurable LC devices such as steerable antennas [5], phase shifters [6][7][8][9][10], and filters [11][12][13][14][15][16] have been reported in the literature.…”

Section: Introductionmentioning

confidence: 99%

Characterization of Nematic Liquid Crystals at Microwave Frequencies

et al. 2020

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The use of nematic liquid crystal (LC) mixtures for microwave frequency applications presents a fundamental drawback: many of these mixtures have not been properly characterized at these frequencies, and researchers do not have an a priori clear idea of which behavior they can expect. This work is focused on developing a new procedure for the extraction of the main parameters of a nematic liquid crystal: dielectric permittivity and loss tangent at 11 GHz under different polarization voltages; splay elastic constant K11, which allows calculation of the threshold voltage (Vth); and rotational viscosity γ11, which allows calculating the response time of any arbitrary device. These properties will be calculated by using a resonator-based method, which is implemented with a new topology of substrate integrated transmission line. The LC molecules should be rotated (polarized) by applying an electric field in order to extract the characteristic parameters; thus, the transmission line needs to have two conductors and low electric losses in order to preserve the integrity of the measurements. This method was applied to a well-known liquid crystal mixture (GT3-23002 from MERCK) obtaining the permittivity and loss tangent versus bias voltage curves, the splay elastic constant, and the rotational viscosity of the mixture. The results validate the viability of the proposed method.

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Section: Introductionmentioning

confidence: 99%

Characterization of Nematic Liquid Crystals at Microwave Frequencies

et al. 2020

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“…In addition, as a voltage-controlled tunable material, liquid crystal can be used in microwave and millimeter wave passive devices such as frequency tunable filters [9]- [11], phase shifters [12]- [14] and reconfigurable antennas [15]- [18]. Its advantages include continuous frequency tuning, high tuning linearity, low loss, low working voltage, light weight, small size, and easy preparation [19].…”

Section: Introductionmentioning

confidence: 99%

Tunable Microwave Bandpass Filters With Complementary Split Ring Resonator and Liquid Crystal Materials

Jiang

Liu

et al. 2019

IEEE Access

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In this paper, a novel planar waveguide filter based on liquid crystal materials is devised, and a half-mode corrugated substrate integrated waveguide (HMCSIW) tunable bandpass filter with complementary split ring resonator (CSRR) structure is proposed. The HMCSIW uses an array of quarter-wave opencircuit stubs to replace conventional substrate integrated waveguide (SIW). While retaining the original cutoff frequency of corrugated substrate integrated waveguide (CSIW), we reduce the circuit size by splitting the central axis to achieve the miniaturization. By utilizing band-stop features of the CSRR in microstrip structure and combining with the electronically controlled dielectric constant of liquid crystal materials with high modulation efficiency of inverted microstrip line structure, a CSRR-loaded HMCSIW bandpass filter with liquid crystal materials is implemented. The experimental results demonstrate that the center frequency of the new filter can be adjusted in a range of 0.65 GHz, the pass-band insertion loss is less than 3.4 dB, the return loss is less than-10 dB, and the structure size is 32 mm×76 mm, which verify that the designed tunable band-pass filter achieves good frequency selection performance. INDEX TERMS Tunable band-pass filter, half-mode corrugated substrate integrated waveguide (HMCSIW), complementary split ring resonator (CSRR), liquid crystal.

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“…In [26], a microwave phase shifter based on anisotropic LC was presented. To the latest contributions, tunable BPFs using LC were developed in [27], [28].…”

Section: Introductionmentioning

confidence: 99%

Tunable Bandstop HMSIW Filter With Flexible Center Frequency and Bandwidth Using Liquid Crystal

Xu¹,

Zhang²,

Peng³

et al. 2019

IEEE Access

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This paper reports on a tunable bandstop filter (BSF) with both flexible center frequency and bandwidth. The tunable BSF is based on half-mode substrate integrated waveguide (HMSIW), of which the broadside is coupled with reconfigurable resonators. Using liquid crystal (LC) material as the substrate, a tunable stopband could be obtained by adjusting the bias voltage of the interdigitated microstrip resonator on LC. In order to increase the tunable range of stopband bandwidth, two additional open resonators are implemented at the broadside of HMSIW cavity. For practical validation, the bandstop HMSIW filter using LC is designed and fabricated. Numerical results demonstrate that,by adjusting the voltages of three resonators on LC, either the lower or the higher cutoff frequency could be controlled independently, leading to the flexible and independent tuning ranges of both center frequency from 4.9 to 5.4 GHz and 3-dB bandwidth of stopband from 1.2 to 1.8 GHz (@5.1 GHz). INDEX TERMS Bandstop filter (BSF), half-mode substrate integrated waveguide (HMSIW), liquid crystal (LC), tunable filter.

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Tunable Liquid Crystal Filter in Nonradiative Dielectric Waveguide Technology at 60 GHz

Cited by 38 publications

References 6 publications

Characterization of Nematic Liquid Crystals at Microwave Frequencies

Characterization of Nematic Liquid Crystals at Microwave Frequencies

Tunable Microwave Bandpass Filters With Complementary Split Ring Resonator and Liquid Crystal Materials

Tunable Bandstop HMSIW Filter With Flexible Center Frequency and Bandwidth Using Liquid Crystal

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