Broad-band microwave characterization of liquid crystals using a temperature-controlled coaxial transmission line

Mueller, Stefan; Penirschke, Andreas; Damm, Christian; Scheele, P.; Wittek, Michael; Weil, C.; Jakoby, Rolf

doi:10.1109/tmtt.2005.848842

Cited by 111 publications

(56 citation statements)

References 8 publications

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“…In what it follows, some of these methods are mentioned. One class of these methods are based on using materials with tunable electromagnetic parameters by bias voltage, such as liquid crystal [12][13][14][15][16][17], Barium Strontium Titanate (BST) [18] and ferroelectric materials [18][19][20]. The other class is based on using the electronical elements such as PIN diodes [21,22] [28].…”

Section: Introductionmentioning

confidence: 99%

A Novel Bandwidth Enhancement Technique for X-Band Rf Mems Actuated Reconfigurable Reflectarray

Ra’di¹,

Nikmehr²,

Poorziad³

2011

PIER

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Abstract-In this paper, a wideband microstrip antenna for Xband (8.2 GHz-12.4 GHz) applications is introduced. First, simple patch antennas are studied, and a narrowband reflectarray antenna is designed. The resultant design demonstrates better performance than the previously published narrowband microstrip reflectarray antennas. The important features of the employed elements are simple structure, linear operation, and use of Radio Frequency Micro Electro Mechanical Systems (RF MEMS) switches for programmable pattern control. Next, employing our novel method, the designed narrowband structure is converted to broadband reflectarray antenna that can cover the whole X band. This novel idea is based on introducing several ground plane slots and controlling their electrical lengths by RF MEMS switches. By means of this method, 952 and 587 degree phase swing are achieved for continuous and discrete slot length variations, respectively. Application of this method along with smaller switches results in phase swing improvement of up to 1616 degree. In all structures a RT duroid (5880) substrate is selected to lower the back radiation. The achieved return loss in all cases is less than 0.32 dB. In comparison with the previous publications, our novel bandwidth enhancement technique has more generalization capability and results in single layered broadband reconfigurable microstrip reflectarray antennas with linear phase swing, lower cost, and ease of RF MEMS implementation.

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Section: Introductionmentioning

confidence: 99%

A Novel Bandwidth Enhancement Technique for X-Band Rf Mems Actuated Reconfigurable Reflectarray

Ra’di¹,

Nikmehr²,

Poorziad³

2011

PIER

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“…Nematic liquid crystals are uni-axial, characterized by refractive indices n and the n ⊥ , for light polarization parallel and orthogonal to the director axis, respectively. The magnitude of nematic birefringence Δn = n − n ⊥ is among the largest of all known materials, on the order of 0.2 that holds from the visible through far infrared and well into the microwave regime [1][2][3][41][42][43][44][45][46][47][48], c.f. Figure 3 and Table 1.…”

Section: F Figures 2(a)-(b)mentioning

confidence: 99%

“…Figure 3 and Table 1. NLC with birefringence approaching unity in the visible regime are now routinely being produced [47,48], and there are increasing efforts to synthesize NLC with large birefringence and low loss in the Terahertz and longer wavelength regime [41][42][43][44][45][46] paralleling the growth in interests in developing tunable electromagnetic devices.…”

Section: F Figures 2(a)-(b)mentioning

confidence: 99%

MULTIPLE TIME SCALES OPTICAL NONLINEARITIES OF LIQUID CRYSTALS FOR OPTICAL-TERAHERTZ-MICROWAVE APPLICATIONS (Invited Review)

Khoo¹,

Zhao²

2014

PIER

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Abstract-We provide a critical account of the dynamics of laser induced refractive index changing mechanisms in nematic liquid crystals which may be useful for all-optical switching and modulation applications in the visible as well as the Terahertz and long-wavelength regime. In particular, the magnitude and response times of optical Kerr effects associated with director axis reorientation, thermal and order parameter changes, coupled flow-reorientation effects and individual molecular electronic responses are thoroughly investigated and documented, along with exemplary experimental demonstrations. Emphases are placed on identifying parameter sets that will enable all-optical switching with much faster response times compared to their conventional electro-optics counterparts.

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“…Due to the display mass market LC materials are accessible, and fabrication methods can be derived from display technology that can make LC based microwave devices highly cost effective [15]. Some LC compounds have been shown to possess a large anisotropy at microwave frequencies [8,16]. The dielectric anisotropy in the microwave region correlates with the material's birefringence in the visible range [8].…”

Section: Introductionmentioning

confidence: 99%

Broad spectrum measurement of the birefringence of an isothiocyanate based liquid crystal

Trushkevych

et al. 2010

Appl. Opt.

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(2010) Broad spectrum measurement of the birefringence of an isothiocyanate based liquid crystal. Applied Optics, 49 (28). pp. 5212-5216. Permanent WRAP URL:http://wrap.warwick.ac.uk/92169 Copyright and reuse:The Warwick Research Archive Portal (WRAP) makes this work by researchers of the University of Warwick available open access under the following conditions. Copyright © and all moral rights to the version of the paper presented here belong to the individual author(s) and/or other copyright owners. To the extent reasonable and practicable the material made available in WRAP has been checked for eligibility before being made available.Copies of full items can be used for personal research or study, educational, or not-for-profit purposes without prior permission or charge. Provided that the authors, title and full bibliographic details are credited, a hyperlink and/or URL is given for the original metadata page and the content is not changed in any way. Publisher's statement:© 2010 Optical Society of America]. Users may use, reuse, and build upon the article, or use the article for text or data mining, so long as such uses are for non-commercial purposes and appropriate attribution is maintained. All other rights are reserved. A note on versions:The version presented here may differ from the published version or, version of record, if you wish to cite this item you are advised to consult the publisher's version. Please see the 'permanent WRAP URL' above for details on accessing the published version and note that access may require a subscription.

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Broad-band microwave characterization of liquid crystals using a temperature-controlled coaxial transmission line

Cited by 111 publications

References 8 publications

A Novel Bandwidth Enhancement Technique for X-Band Rf Mems Actuated Reconfigurable Reflectarray

A Novel Bandwidth Enhancement Technique for X-Band Rf Mems Actuated Reconfigurable Reflectarray

MULTIPLE TIME SCALES OPTICAL NONLINEARITIES OF LIQUID CRYSTALS FOR OPTICAL-TERAHERTZ-MICROWAVE APPLICATIONS (Invited Review)

Broad spectrum measurement of the birefringence of an isothiocyanate based liquid crystal

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