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

Jiang, Di; Liu, Yupeng; Li, Xiaoyu; Wang, Guofu; Zheng, Zhi

doi:10.1109/access.2019.2924194

Cited by 33 publications

(20 citation statements)

References 22 publications

(18 reference statements)

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“…Similar to traditional microstrip lines, the liquid crystal inverted microstrip transmission lines propagate quasi-TEM waves. When the liquid crystal material is filled between the microstrip line and the ground, and the thickness of the inverted microstrip line is much smaller than that of the dielectric substrate, its characteristic impedance can be expressed as [15]:…”

Section: Theory Of Liquid Crystal a Theory Of Liquid Crystal Micmentioning

confidence: 99%

Millimeter-Wave Broadband Tunable Band-Pass Filter Based on Liquid Crystal Materials

Jiang

et al. 2020

IEEE Access

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In this paper, a wideband band-pass frequency tunable filter using liquid crystal is proposed for millimeter-wave applications, which achieves the band-pass characteristics by introducing four transmission zeros. The main filter structure is the ring resonator loaded with two quarter-wavelength open stubs using inverted microstrip structure. The ring resonator contacts directly with the liquid crystal layer to control the bias voltage to adjust the dielectric constant of the liquid crystal material. Experimental results show that the central frequency reconstruction range varies from 27.7GHz to 24.6GHz, and the corresponding relative bandwidth changes from 48.17% to 49.82%. The group delay within the pass-band is less than 0.45ns before and after the filter reconstruction, which indicates its applicability in K-band filter. INDEX TERMS Wideband bandpass filter, tunable, liquid crystal, ring resonator.

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Section: Theory Of Liquid Crystal a Theory Of Liquid Crystal Micmentioning

confidence: 99%

Millimeter-Wave Broadband Tunable Band-Pass Filter Based on Liquid Crystal Materials

Jiang

et al. 2020

IEEE Access

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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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“…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%

“…In practice, the depth of the rectangular groove includes the thickness of coating material and LC cell.3 Similar to[28], the specific values of parameters (ε ⊥ = 2.4, ε = 3.3, tanδ ⊥ = 0.007 and tanδ = 0.0022) are of references for simulations.…”

mentioning

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

Cited by 33 publications

References 22 publications

Millimeter-Wave Broadband Tunable Band-Pass Filter Based on Liquid Crystal Materials

Millimeter-Wave Broadband Tunable Band-Pass Filter Based on Liquid Crystal Materials

Characterization of Nematic Liquid Crystals at Microwave Frequencies

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

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